Dynamic power allocations for direct broadcasting satellite (dbs) channels via wavefront multiplexing

ABSTRACT

A direct broadcasting satellite (DBS) system features a capability of coherently combining amplified signals powers from various broadcasting transponders without modifying the satellite segment. Organized DBS transponders would function as an equivalent DBS transponder with a higher EIRP. Power allocations are via a mechanism in an uplink transmitter in a ground segment and power combining mechanisms are in user receivers in a user segment. Specifically, the transmitter generates mixtures of input signals by using Wavefront-Multiplexing and transmits wavefront-multiplexed (WFM) signals which are sent concurrently through multiple parallel channels of transponders in the satellite segment. A receiver in the user segment separates the mixtures of received amplified WFM signals and coherently combines amplified components by various transponders by adaptive equalizing and Wavefront De-Multiplexing processors. The WFM signal mixtures allow an operator, or automated system, at the transmitter to dynamically allocate the equivalent transponder powers according to continuously changing demands.

RELATED APPLICATION DATA

This application is a continuation of application Ser. No. 13/303,781,filed on Nov. 23, 2011, now pending, which is a continuation in part ofapplication Ser. No. 12/462,145, filed on Jul. 30, 2009, now U.S. Pat.No. 8,111,646.

BACKGROUND OF THE INVENTION

(1) Technical Field

The present invention relates to the fields of communications systemsand computer networks and, in particular, to satellite networks,Direct-Broadcast-Service (DBS) broadcasting architectures, DBS uplinkterminals, and DBS receive only subscriber ground terminals. Morespecifically, but without limitation thereto, the present inventionpertains to a communication system and method that allows a transmittersegment (operator at uplink segment) to dynamically combine power fromplurality of propagation channels (transponders) in order to improvepower levels of signals being transmitted, without affecting thereceiver segment (downlink segment) and the propagation segment (spacesegment), and without modifying the configuration of the propagationapparatus (satellite).

(2) Description of Related Art

Current direct-broadcast-service (DBS) satellite networks deliver manytelevision (TV) programs over coverage areas via dedicated broadcastingsatellites in geostationary orbits. DBS refers to satellite TV systemsin which the subscribers, or end users, receive signals directly fromgeostationary satellites. A DBS subscriber installation consists of adish antenna with a diameter between 50 to 90 centimeters, aconventional TV set, a signal converter placed next to the TV set (theset-top box), and a length of coaxial cable between the dish and theconverter. Generally, the dish antenna intercepts the microwave signalstransmitted directly from the satellite and the converter producesoutput signals that can be viewed on the TV receiver.

At the present time, the geostationary satellite orbit is the style mostwidely used for broadcasting, where the satellite is in an equatorialorbit and appears to be at a fixed point in the sky relative to anobserver on the earth. The trend in the industry is to traditionally usethe satellite in the “bent pipe” mode, where, as the term suggests, thesatellite acts like a slingshot to redirect the incoming signal todifferent locations on earth. As a result, video coverage of an event atone place on the globe can be sent up to a satellite and redistributed(broadcast) over large areas of the populated world in the form of cleartelevision pictures.

Generally, the signals are broadcast in digital format at microwavefrequencies above 10¹⁰ Hertz (upper portion of the microwave Kufrequency band). As a result, the downlink, from satellite to earth,operates at frequencies between 12.2 Gigahertz (GHz) and 12.7 GHz.Accordingly, geo-satellite based direct TV broadcasting systems featureshigh power Ku-satellites (transmitting at microwave frequencies above 10GHz) and receiving-only ground terminals with small dishes. Thesesatellite systems are very attractive for satisfying the wide area ofcoverage and the point-to-multipoint nature required for broadcasting.

Currently, operators over North America for full continental UnitedStates coverage utilize a group of multiple high-power or medium powersatellites. These satellites fall into the category of eitherBroadcasting Satellite Service (BSS) or Fixed Satellite Service (FSS).Each satellite has many transponders, analogous to channels on atelevision receiver except that each transponder is capable of carryingmany television signals simultaneously. These satellites, with maximumangular separations less than 25° in the geostationary arc, form amini-constellation that can be simultaneously viewed by small, fixed,and round DBS antennas.

Perhaps, the two most important and most limiting assets of broadcastingsatellites are the total available “satellite bandwidth” and “radiatedpower.” Although the information carrying capacity of satellites hasbeen expanding steadily over the years since its inception, theavailable satellite bandwidth is still very small compared to theoptical fiber bandwidth capabilities. This is particularly critical forthe case of video transmission or high-speed data throughput, wherethere are severe limitations affecting the large bandwidth required bythese transmissions. Progress in digital compression techniques isgradually reducing the bandwidth needed for video transmission. However,full-motion video still requires several Megabits per second.

Regarding the radiated power requirements of satellite communicationsystems, the radiated power levels and coverage antenna gains ofbroadcasting satellites dictate and limit the size and availability ofsubscriber terminals. As the technology moved forward in the last twodecades, the available power for communications payloads on satellitesincreased from less than 100 watts (W) to over twenty kilowatts (20 kW).

Usually, satellite designs are initially optimized and balanced on bothsatellite bandwidth frequency and power assets for a given missionrequirement, wherein it is considered to be a good practice to have bothassets equally balanced, such as not to allow one of the two assets toreserve more space than the other. However, as time passes by, themission requirement may change in time in a highly dynamic businessenvironment. Therefore, the initial designs with balanced satelliteassets may become non-optimal, as time passes by, and excessive spacefrequency and/or excessive power assets may become available for otherapplications at some points in time. As such, there is a need for adynamic communication system that will take advantage of these freeexcessive power satellite assets dynamically available at some points intime to be utilized for other applications.

For the foregoing reasons, there is a great need in satellitecommunications for a system that allows an operator to dynamicallyallocate any existing available excess satellite radiated power tovarious programs (signals being transmitted) via multiple transpondersin a satellite, or among multiple satellites, in order to improve thepower levels of the various programs (signals being transmitted).Furthermore, there is a need for the dynamic power allocation to becontrolled by the uplink segment (terminals or transmitter segment)without affecting the user-end of downlink segment (receiver segment)and the space segment (propagation segment), and without modifying thesatellite configuration. In addition, for the dynamic power allocationto be successful, the receiving-only terminals must “coherently combine”the radiated power from the various transponders in order to enhancedifferent broadcasting programs.

An embodiment of the present invention involves a dynamic improvement ofradiated power over coverage areas by utilizing additional transponderson a satellite or from different satellites that are not being utilizedat their full capacity and that have excessive (unused) radiated poweravailable to be utilized, where the effective dynamic power allocationsare utilized and implemented through the ground segment (transmittersegment or uplink segment) only, without affecting the space segment(propagation segment) configuration at all.

In addition to applications in satellite communications, there is agreat need in communication systems in general to allow a user or anautomated transmission system (transmitter segment) to dynamicallyallocate any existing available excess radiated power from propagationchannels (in the propagation segment) to various applications, in orderto improve power levels of transmitted signals and without affecting thereceiver segment and the propagation segment (transmission medium,propagation apparatus, and propagation channels) of the communicationsystem, and without modifying the configuration (infrastructure) of thepropagation apparatus and propagation channels.

Some non-limiting and non-exhaustive examples of such communicationssystems (needing to dynamically allocate existing excess power availablefrom propagation channels in order to improve power levels oftransmitted signals without affecting the receiver segment and thepropagation segment) are: wireless communication systems, fiber opticalcommunication systems, wire communication systems, radio frequencycommunication systems, satellite communication systems, sonarcommunication systems, radar communication systems, laser communicationsystems, internet communication systems, communication systems between avehicle and a satellite, communication systems between a least twovehicles, internal vehicle communication systems between the variousoperating subsystems within a vehicle, and any communication systemsresulting from a combination of at least two of these communicationsystems therein.

The following references are presented for further backgroundinformation:

-   [1] D. Chang, W. Mayfield, J. Novak III, and F. Taormina, “Phased    Array Terminal for Equatorial Satellite Constellations,” U.S. Pat.    No. 7,339,520, Mar. 4, 2008; and-   [2] D. Chang, W. Lim, and M. Chang, “Multiple Dynamic Connectivity    for Satellite Communications Systems,” U.S. Pat. No. 7,068,616, Jun.    27, 2006.

SUMMARY OF THE INVENTION

The present invention provides a dynamic communication system suitablefor dynamically combining power from a plurality of propagation channelsin order to improve power levels of transmitted signals, wherein dynamicpower allocation is implemented through a transmitter segment withoutaffecting receiver segment and propagation segment, and withoutmodifying the configuration of the propagation apparatus, the systemcomprising: a processor and a memory coupled with the processor. Thedynamic communication system further comprises an input coupled with theprocessor for receiving a plurality of signals to be transmitted.Generally, the transmitter segment generates mixtures of the inputsignals to be transmitted by using a Wavefront-Multiplexing transformand transmits the wavefront-multiplexed (WFM) signals, throughpropagation channels, to a receiver segment. In turn, the receiversegment (using adaptive equalization and Wavefront-De-Multiplexing)coherently separates the mixtures of received WFM signals into theindividual spatial-domain signals that were initially inputted into thesystem to be transmitted. The WFM signal mixtures allow an operator, oran automated system, at the transmitter segment to dynamically allocateequivalent channel (transponder) powers according to continuouslychanging market demands by dynamically including change of relativeinput powers into ratios of the WFM signal mixtures being transmitted.

Furthermore, the dynamic communication system comprises an outputcoupled with the processor for outputting the individual spatial-domainsignals that were coherently separated by the receiver segment, andinstruction means residing in its processor and memory, such that theinstruction means are executable by the processor for causing theprocessor to perform operations of: transforming the input signals byperforming a Wavefront-Multiplexing transform (WFM transform);transmitting the wavefront multiplexed signals (WFM signals) over atransmission medium through propagation channels, wherein there exist atleast as many propagation channels as there exist WFM signals and eachWFM signal is transmitted over its own propagation channel; receivingthe transmitted WFM signals from the propagation channels; performingadaptive equalization on received WFM signals in order to account forpropagation channel effects, wherein the propagation channel effectscomprise dynamic differential propagation effects due to thetransmission medium and static differential propagation effectscomprising unbalanced amplitudes, unbalanced phases, and unbalancedtime-delays between the received WFM signals and the WFM signalsoutputted by the WFM transform; and separating the equalized WFM signalsinto individual spatial-domain signals by performing aWavefront-De-Multiplexing transform (WFDM transform). The dynamiccommunication system outputs, in a computationally efficient manner, theindividual spatial-domain signals that were coherently separated by thereceiver segment from the mixtures of WFM signals transmitted by thetransmitter segment.

An embodiment of the invention selects the dynamic communication systemfrom a group consisting of a: wireless communication system, fiberoptical communication system, wire communication system, radio frequencycommunication system, satellite communication system, sonarcommunication system, radar communication system, laser communicationsystem, internet communication system, communication system between avehicle and a satellite, communication system between a least twovehicles, internal vehicle communication system between the variousoperating subsystems within a vehicle, and a communication systemresulting from a combination of at least two of these communicationsystems therein.

In an embodiment of the invention, an operator or an automatedtransmission system, at a transmitter segment, dynamically allocatesequivalent propagation channel powers according to continuously changingapplication demands by dynamically including change of relative inputpowers into ratios of mixtures of the input signals, in order to improveradiated power of the input signals being transmitted. In thisembodiment, the dynamic power allocation is implemented through thetransmitter segment without affecting receiver segment and propagationsegment, and without modifying configuration of a propagation apparatusand the propagation channels in the propagation segment.

In an further embodiment of the invention, the input signals arereceived at a ground end of an uplink segment and the input signalscomprise digital signals, analog signals, mixed analog and digitalsignals, and a plurality of digital signal streams to be transmitted toa satellite with a number of transponders operating at a plurality offrequencies, wherein there exists at least as many transponders in thesatellite as there exist received digital signal streams.

In another embodiment, at the uplink segment (transmitter segment) thesystem further comprises the operations of: transforming, at the uplinksegment, the WFM signals to a satellite frequency band, prior totransmitting the WFM signals to a satellite segment; and uploading, atthe uplink segment, the transformed WFM signals to the satellitesegment. In this embodiment, the system also further comprises theoperations of: transmitting through the satellite transponders, at thesatellite segment (propagation segment), the transformed WFM signals toa downlink segment; downloading, at the downlink segment (receiversegment), the transformed WFM signals transmitted from the satellitesegment; processing, at a user end of the downlink segment, thedownloaded transformed WFM signals to a base-band frequency resulting inbase-band frequency WFM signals, wherein the adaptive equalization isperformed on the base-band frequency WFM signals in order to account forpropagation channel effects from the channels on the transponders of asatellite; recovering the individual spatial-domain digital signalstreams received from the transmitting subsystem by amplifying,filtering, synchronizing, and demodulating the individual spatial-domainsignals from the WFDM; and outputting the recovered input digital signalstreams.

In a further embodiment of the invention, in the operation of separatingequalized WFM signals, the WFDM transform equals the unique inversetransform of the WFM transform, whereby the WFDM transform separates theWFM signals into individual spatial-domain signals. Furthermore, in theoperation of transforming input signals by WFM, the transformed WFMsignals are uploaded from a ground end of the uplink segment to asatellite via an uplink ground antenna and the WFM transform comprises anumber of input ports and a number of output ports, where the number ofinput ports equals the number of output ports and where the number ofoutput ports equals the number of transponders.

In yet another embodiment, the WFM transform further comprises theoperations of: inputting digital signal streams to the WFM input ports,wherein an individual WFM input port is connected to only onecorresponding input digital signal stream; inputting, at the ground endof uplink segment when there are more transponders than there are inputdigital signal streams, a control signal into WFM input ports notconnected to digital signal streams; inputting, at the ground end ofuplink segment when the number of transponders equals the number ofdigital signal streams, a control signal into a WFM input port connectedto a digital signal stream by time-multiplexing the WFM input portbetween the control signal and the digital signal stream; performing anorthogonal functional transformation from a spatial-domainrepresentation of the inputted digital signal streams to awavefront-domain representation of the inputted digital signal streams,wherein a necessary and sufficient condition of the WFM transform isthat the WFM transform has a realizable unique inverse, and wherein thewavefront representation of the received digital signal streamscomprises a plurality of output WFM signals, wherein each output WFMsignal is comprised of a unique linear combination of all the receivedspatial-domain digital signal streams inputted into the WFM transform,and wherein the output WFM signals are orthogonal to one another; andoutputting the WFM signals to the WFM output ports.

Another embodiment of the present invention is a one-way communicationsystem selected from a group consisting of: a direct broadcast service(DBS), a fixed satellite service (FSS), a mobile satellite service(MSS), a ground uplink station broadcasting to a ground downlinkstation, a ground uplink station broadcasting to a user end of downlinksegment or to a network hub, a user end of uplink segment transmittingto a user end of downlink segment, a user end of uplink segmenttransmitting to a network hub or to a ground downlink station, a networkhub transmitting to a ground station, and a network hub transmitting toanother network hub.

In an embodiment of the operation of performing adaptive equalization, aWFM input port connected to a control signal has a corresponding WFDMcontrolled output port at the user end of downlink segment, such thatthe WFDM controlled output ports are used as diagnostic ports, and acost function is used to measure a difference between controlled inputports and their corresponding diagnostic ports, whereby the costfunction is minimal when adaptive equalization is reached. Thisembodiment of the operation of performing adaptive equalization furtherutilizes a gradient cost function, an optimization processor, and anamplitude, phase, and time-delay compensation processor.

In the previous embodiment, the adaptive equalization is performed byoperations of: measuring the gradient cost function outputted from theWFDM; performing optimization processing on the measured gradient costfunction by using a steepest descent technique to reach an optimalsolution, wherein the optimal solution corresponds to dynamicallyeliminating unbalanced amplitudes, unbalanced phases, and unbalancedtime-delays between the output WFM signals from the WFM transform andthe base-band frequency WFM signals at the user end of the downlinksegment, and wherein the optimization processor sends equalizationcontrol signals to the amplitude, phase, and time-delay compensationprocessor; performing amplitude, phase, and time-delay compensation byadjusting the amplitude, phase, and time-delay of the receiveddown-converted WFM signals in accordance to the equalization controlsignals from the optimization processor in order to reduce the costfunction; separating WFM signals from the adaptive equalizationoperation into individual spatial-domain signals and control signals byperforming a WFDM transform; and iterating, at the user end of downlinksegment, between the operations of measuring the gradient cost function,performing optimization processing, performing amplitude, phase, andtime-delay compensation, and separating the WFM signals from theadaptive equalization operation, until an optimal solution is reachedand the cost function is minimal.

In another embodiment of the invention, an operator, at the ground endof uplink segment or at a program aggregation facility for a DBSservice, dynamically allocates equivalent transponder powers accordingto continuously changing market demands by dynamically including changeof relative input powers into ratios of mixtures of the input digitalsignal streams, in order to improve radiated power of the input digitalsignal streams being broadcasted. In this embodiment, the dynamic powerallocation is implemented through the ground end of uplink segmentwithout affecting the user end of downlink segment and the spacesegment, and without modifying satellite configuration.

In a further embodiment, a plurality of digital signal streams from atransmitting subsystem are transmitted to multiple designated satellitesat various orbital slots, wherein the WFM signals are transmittedthrough a transponder in each satellite, and wherein there exists atleast as many transponders available for transmission as there existreceived digital signal streams to be transmitted. Furthermore, the WFMsignals are uploaded to designated satellites via a multiple beamantenna, multiple antennas, or a combination of multiple beam antennawith multiple antennas at the ground end of uplink segment, and themultiple designated satellites at various orbital slots are accessed bythe user end of downlink segment via a multiple beam antenna.

In still a further embodiment, a plurality of input digital signalstreams from a transmitting subsystem are transmitted to a plurality ofsatellite configurations comprised of a satellite, with a number oftransponders operating at different frequencies, combined with multipledesignated satellites at various orbital slots, such that the WFMsignals are transmitted through a transponder in each satellite. Inaddition, the WFM signals are uploaded to the multiple satellites via amultiple beam antenna, multiple antennas, or a multiple beam antennacombined with multiple antennas at the ground end of uplink segment, andthe multiple designated satellites are accessed by a user end ofdownlink segment via a multiple beam antenna.

An additional embodiment of the invention combines the equalizedamplitudes, equalized phases, and equalized time-delays in the equalizedWFM signals with associated optimization techniques to perform backchannel calibration on mobile satellite communications with ground basedbeam forming features (GBBF).

In another embodiment, the unique inverse of the WFM transform is equalto the WFM transform and the WFDM transform equals the WFM transform,and the WFM transform is implemented at digital base band in digitalformat or by analog devices, wherein the analog devices are selectedfrom a group consisting of a Butler Matrix, a Fourier transform pair,and a Hartley transform pair.

A further embodiment of the operation of performing adaptiveequalization utilizes a cost function selected from a group consistingof a difference between a controlled input port and its correspondingdiagnostic port, Signal to Noise Ratio (SNR), and Bit Error. In thisembodiment, the control signals comprise ground (zero value) signals andthe gradient cost function corresponds to a sum of detected power levelsat the diagnostic ports of the WFDM, whereby when adaptive equalizationis reached the gradient cost function is zero and there are nodetectable power levels in the diagnostic ports.

In still a further embodiment of the invention, the WFM transform isimplemented at digital base band in digital format or by analog devices,wherein the analog devices are selected from a group consisting of aButler Matrix, a Fourier transform pair, and a Hartley transform pair.

In yet another embodiment of the invention, the unique inverse of theWFM transform is equal to the WFM transform, and the WFDM transformequals the WFM transform.

Another embodiment of the invention is a two-way dynamic satellitecommunication system comprising at least two transmitter segments and atleast two receiver segments, with the transmitter segments comprising aground end of uplink segment and a user end of uplink segment, and thereceiver segments comprising a user end of downlink segment and a groundend of downlink segment, such that the ground segments (uplink anddownlink) and the user segments (downlink and uplink) transmit andreceive a plurality of digital signal streams back and forth between theground segments and the user segments.

In this two-way communication embodiment, the user end of uplink segmenttransmits a plurality of digital signal streams to the ground end ofdownlink segment via a satellite, with a number of transpondersoperating at a plurality of frequencies, by performing the operationsof: transforming, at the user end uplink segment, digital signal streamsby performing a WFM transform; frequency up-converting the output WFMsignals to distinct frequency carriers within frequency bands forsatellite communications; amplifying frequency up-converted WFM signalsand frequency multiplexing (FDM) the amplified WFM signals by utilizinga standard multiplexer (MUX) at the satellite frequency band; uploadingWFM signals at the satellite frequency band to the satellite via anuplink user antenna; receiving and frequency translating the carrierfrequencies of the WFM signals in the satellite segment; amplifying andtransmitting the frequency translated WFM signals through the satellitetransponders to the ground end of downlink segment, whereby alldesignated transponders in the satellite are being utilized to transmittranslated WFM signals.

Furthermore, in the two-way communication embodiment, the ground end ofdownlink segment receives a plurality of digital signal streams from theuser end of uplink segment by performing the operations of: receivingand amplifying, at the ground end of downlink segment, the frequencytranslated WFM signals from the transponders; frequency down-convertingthe amplified frequency translated WFM signals to a common IF orbase-band frequency; performing adaptive equalization on down-convertedWFM signals at the ground end of downlink segment; separating equalizedWFM signals into individual spatial-domain signals by performing a WFDMtransform; and recovering the individual spatial-domain digital signalstreams transmitted by the user end of uplink segment by amplifying,filtering, synchronizing, and demodulating the individual spatial-domainsignals from the WFDM.

In another two-way communication embodiment, the two-way satellitecommunication system comprises fixed satellite services (FSS) and mobilesatellite services (MSS), selected from a group consisting of: a grounduplink station communicating with a receiving ground station, a user endsegment communicating with another user end segment, a user end segmentcommunicating with a network hub or a ground station, a network hubcommunicating with a ground station, and a network hub communicatingwith another network hub.

In a two-way communication embodiment of the operation of performingadaptive equalization at the downlink segments (receiver segments), aWFM input port connected to a control signal, at the uplink segments(transmitter segments), has a corresponding WFDM controlled output portat the downlink segments (receiver segments), such that the WFDMcontrolled output ports are used as diagnostic ports, and a costfunction is used to measure a difference between controlled input portsand their corresponding diagnostic ports, whereby the cost function isminimal when adaptive equalization is reached. This two-waycommunication embodiment of the operation of performing adaptiveequalization further utilizes a gradient cost function, an optimizationprocessor, and an amplitude, phase, and time-delay compensationprocessor.

In the previous two-way communication embodiment, the adaptiveequalization is performed by operations of: measuring the gradient costfunction outputted from the WFDM; performing optimization processing onthe measured gradient cost function by using a steepest descenttechnique to reach an optimal solution, wherein the optimal solutioncorresponds to dynamically eliminating unbalanced amplitudes, unbalancedphases, and unbalanced time-delays between the output WFM signals fromthe WFM transform and the base-band frequency WFM signals at the groundend and user end of the downlink segments, and wherein the optimizationprocessor sends equalization control signals to the amplitude, phase,and time-delay compensation processor; performing amplitude, phase, andtime-delay compensation by adjusting the amplitude, phase, andtime-delay of the received down-converted WFM signals in accordance tothe equalization control signals from the optimization processor inorder to reduce the cost function; separating WFM signals from theadaptive equalization operation into individual spatial-domain signalsand control signals by performing a WFDM transform; and iterating, atthe downlink segments, between the operations of measuring the gradientcost function, performing optimization processing, performing amplitude,phase, and time-delay compensation, and separating the WFM signals fromthe adaptive equalization operation, until an optimal solution isreached and the cost function is minimal.

In another two-way communication embodiment of the invention, anoperator, at the ground end of uplink segment or at the user end ofuplink segment, dynamically allocates equivalent transponder powersaccording to continuously changing market demands by dynamicallyincluding change of relative input powers into ratios of mixtures of theinput digital signal streams, in order to improve radiated power of theinput digital signal streams being broadcasted. In this two-waycommunication embodiment, the dynamic power allocation is implementedthrough the uplink segments without affecting the downlink segments andthe space segment, and without modifying satellite configuration.

In a further two-way communication embodiment, a plurality of digitalsignal streams from an uplink segment are transmitted to multipledesignated satellites at various orbital slots, wherein the WFM signalsare transmitted through a transponder in each satellite, and whereinthere exists at least as many transponders available for transmission asthere exist received digital signal streams to be transmitted.Furthermore, the WFM signals are uploaded, at the uplink segments, todesignated satellites via a multiple beam antenna, multiple antennas, ora combination of multiple beam antenna with multiple antennas, and themultiple designated satellites at various orbital slots are accessed bythe downlink segments via a multiple beam antenna, multiple antennas, ora combination of multiple beam antenna with multiple antennas.

In still a further two-way communication embodiment, a plurality ofinput digital signal streams from the uplink segments are transmitted toa plurality of satellite configurations comprised of a satellite, with anumber of transponders operating at different frequencies, combined withmultiple designated satellites at various orbital slots, wherein the WFMsignals are transmitted through a transponder in each satellite. Inaddition, the WFM signals are uploaded to the multiple satellites via amultiple beam antenna, multiple antennas, or a multiple beam antennacombined with multiple antennas at the uplink segment, and wherein themultiple designated satellites are accessed by the downlink segments viaa multiple beam antenna, multiple antennas, or a combination of multiplebeam antenna with multiple antennas.

An additional two-way communication embodiment of the invention combinesthe equalized amplitudes, equalized phases, and equalized time-delays inthe equalized WFM signals with associated optimization techniques toperform back channel calibration on mobile satellite communications withground based beam forming features (GBBF).

In another two-way communication embodiment, the unique inverse of theWFM transform is equal to the WFM transform and the WFDM transformequals the WFM transform, and the WFM transform is implemented atdigital base band in digital format or by analog devices, wherein theanalog devices are selected from a group consisting of a Butler Matrix,a Fourier transform pair, and a Hartley transform pair.

A further two-way communication embodiment of the operation ofperforming adaptive equalization, at the downlink segments, utilizes acost function selected from a group consisting of a difference between acontrolled input port and its corresponding diagnostic port, Signal toNoise Ratio (SNR), and Bit Error. In this two-way embodiment, thecontrol signals comprise ground (zero value) signals and the gradientcost function corresponds to a sum of detected power levels at thediagnostic ports of the WFDM, whereby when adaptive equalization isreached the gradient cost function is zero and there are no detectablepower levels in the diagnostic ports.

In still a further two-way communication embodiment of the invention,the WFM transform is implemented at digital base band in digital formator by analog devices, wherein the analog devices are selected from agroup consisting of a Butler Matrix, a Fourier transform pair, and aHartley transform pair.

In yet another two-way communication embodiment of the invention, theunique inverse of the WFM transform is equal to the WFM transform, andthe WFDM transform equals the WFM transform.

The features of the above embodiments of the present invention may becombined in many ways to produce a great variety of specific embodimentsand aspects of the invention, as will be appreciated by those skilled inthe art. Furthermore, the operations which comprise the variousembodiments above of the dynamic communication system are analogous tothe operations in the various method embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects, features and advantages of the present invention willbecome better understood from the following detailed descriptions of thepreferred embodiment of the invention in conjunction with reference tothe following appended claims, and accompanying drawings where:

FIG. 1 is an illustrative block diagram depicting the components of acomputer system used in the present invention;

FIG. 2 is an illustrative block diagram depicting an embodiment of theinvention;

FIG. 3 is an image illustrating the functionality of the WavefrontMultiplexing transform;

FIG. 4 is a table showing two examples of vector coefficients for anorthogonal transformation matrix used to implement an embodiment of theWavefront Multiplexing transform.

FIG. 5 is an illustrative block diagram contrasting a conventional DBSsatellite system with an embodiment of the invention;

FIG. 6 is an illustrative block diagram depicting an embodiment of theinvention comprising adaptive equalization;

FIG. 7 is a table showing results obtained using a power combiningembodiment of the invention; and

FIG. 8 is an illustrative block diagram depicting an embodiment of theinvention used to combine power from available transponders in a retiredsatellite.

FIG. 9 is an illustrative block diagram depicting an embodiment of theinvention used to combine power from available transponders in two GEOOrbit satellites. The illustration is in return links

FIG. 10 is an illustrative block diagram depicting an embodiment of theinvention used to combine power from available transponders in twonon-GEO Orbit satellites. The illustration is in return links with athird satellite coming to the coverage (service) area.

FIG. 10A is an illustrative block diagram depicting an embodiment of theinvention used to combine power from available transponders in 4 non-GEOOrbit satellites. The illustration is in forward links. The probing (ordiagnostic) signals and associated processing are not depicted.

DETAILED DESCRIPTION

The present invention relates to the fields of communications systemsand computer networks and, in particular, to satellite networks,Direct-Broadcast-Service (DBS) broadcasting architectures, DBS uplinkterminals, and DBS receive only subscriber ground terminals. Morespecifically, but without limitation thereto, the present inventionpertains to a communication system and method that allows a transmittersegment (operator at uplink segment) to dynamically combine power fromplurality of propagation channels (transponders) in order to improvepower levels of signals being transmitted, without affecting thereceiver segment (downlink segment) and the propagation segment (spacesegment), and without modifying the configuration of the propagationapparatus (satellite).

The following description, taken in conjunction with the referenceddrawings, is presented to enable one of ordinary skill in the art tomake and use the invention and to incorporate it in the context ofparticular applications. Various modifications, as well as a variety ofuses in different applications, will be readily apparent to thoseskilled in the art, and the general principles, defined herein, may beapplied to a wide range of embodiments. Thus, the present invention isnot intended to be limited to the embodiments presented, but is to beaccorded the widest scope consistent with the principles and novelfeatures disclosed herein. Furthermore, it should be noted that unlessexplicitly stated otherwise, the figures included herein are illustrateddiagrammatically and without any specific scale, as they are provided asqualitative illustrations of the concept of the present invention.

In order to provide a working frame of reference, first a glossary ofsome of the terms used in the description and claims is given as acentral resource for the reader. The glossary is intended to provide thereader with a general understanding of various terms as they are used inthis disclosure, and is not intended to limit the scope of these terms.Rather, the scope of the terms is intended to be construed withreference to this disclosure as a whole and with respect to the claimsbelow. Next, an overview is presented to provide a general understandingof the scope and meaning of the terms used herein. Thereafter, thephysical embodiments of the present invention are provided to enable thereader to understand the various manifestations of the presentinvention. Finally, a detailed description of the elements is providedin order to enable the reader to make and use the various embodiments ofthe invention without involving extensive experimentation.

(1) Glossary

Before describing the specific details of the present invention, it isuseful to provide a centralized location for various terms used hereinand in the claims. A definition has been included for these variousterms. However, the definition provided should not be consideredlimiting to the extent that the terms are known in the art. Thesedefinitions are provided to assist in teaching a general understandingof the present invention.

Computer readable media—The term “computer readable media,” as usedherein, denotes any media storage device that can interface with acomputer and transfer data back and forth between the computer and thecomputer readable media. Some non-limiting examples of computer readablemedia include: an external computer connected to the system, an internetconnection, a Compact Disk (CD), a Digital Versatile Disk/Digital VideoDisk (DVD), a floppy disk, a magnetic tape, an internet web camera, adirect satellite link, a video cassette recorder (VCR), a removable harddrive, a digital camera, a video camera, a video cassette, an electronicemail, a printer, a scanner, a fax, a solid-state recording media, amodem, a read only memory (ROM), and flash-type memories.

De-Multiplexer—The term “De-Multiplexer,” as used herein, is a standardterm used in the fields of electronics, telecommunications, signalprocessing, digital circuits design, and computer networks to denote aprocess or device that separates or splits a single input signal, thatcarries multiple individual signals within (such as multiple channels ortelephone calls), into multiple output signals, such that the “outputsignals from the demultiplexer” correspond to the individual signalscarried by the single input signal. The aim of a de-multiplexer is toextract the original signals or channels on a receiver side of atransmission system. Generally, a dc-multiplexer is often used on areceiver side of a communication system with a complementary multiplexeron the transmitting side of the communication system.

DEMUX—An acronym for “De-Multiplexer.” The term “DEMUX,” as used herein,is a standard term used in the fields of electronics,telecommunications, signal processing, digital circuits design, andcomputer networks to denote a De-multiplexer which separates or splits asingle input signal, that carries multiple individual signals within,into multiple output signals, such that the “output signals from theDe-multiplexer” correspond to the individual signals carried by thesingle input signal.

Direct-Broadcast-Service (DBS)—The term “Direct-Broadcast-Service,” asused herein, is a standard term used in the field of satellitecommunications to denote a broadcasting service that delivers televisionprograms over coverage areas, via dedicated broadcasting satellites ingeostationary orbits, to small DBS satellite dishes (usually 18 to 24inches or 45 to 60 cm in diameter) operating in the upper portion of themicrowave Ku frequency band. DBS technology is typically used fordirect-to-home (DTH) oriented satellite TV services, such as Direct TV®and DISH Network® in the United States of America.

DBS—An acronym for “Direct-Broadcast-Service.” The term “DBS,” as usedherein, is a standard term used in the field of satellite communicationsto denote a direct-broadcasting-service that delivers televisionprograms over coverage areas, via dedicated broadcasting satellites ingeostationary orbits, to small DBS satellite dishes (usually 18 to 24inches or 45 to 60 cm in diameter) operating in the upper portion of themicrowave Ku frequency band. DBS technology is typically used fordirect-to-home (DTH) oriented satellite TV services.

Fixed-Satellite-Service (FSS)—The term “Fixed-Satellite-Service,” asused herein, is a standard term used in the field of satellitecommunications to denote a broadcasting service that uses the Cfrequency band and the lower portions of the Ku frequency band fortransmission of broadcast feeds to and from television networks andlocal affiliate stations, as well as being for transmissions of distancelearning by schools and universities, video-conferencing, and todistribute national cable channels to cable television head-ends.Fixed-satellite-service (FSS) operates at lower frequency and lowerpower than a direct broadcast service (DBS). The fixed-satellite-servicerequires a much larger dish for reception than DBS, such as 3 to 8 feetin diameter for Ku frequency band transmission and 12 feet in diameterfor C frequency band transmission.

FSS—An acronym for “Fixed-Satellite-Service.” The term “FSS,” as usedherein, is a standard term used in the field of satellite communicationsto denote a fixed-satellite-service that uses the C frequency band andthe lower portions of the Ku frequency band for satellite transmissionof broadcast feeds to and from television networks and local affiliatestations.

Geostationary Satellite Orbit—The term “Geostationary Satellite Orbit,”as used herein, is a standard term used in the field of satellitecommunications to denote a satellite orbit around the planet Earth withan altitude of approximately 35786 km (22240 miles), with an orbitalperiod equal to approximately 24 hours (average rotation time of theEarth), and with an approximately zero orbital inclination in referenceto the equatorial plane of the Earth. To an observer on the ground, ageostationary satellite will appear as a fixed point in the sky.

Geosynchronous Satellite Orbit—The term “Geosynchronous SatelliteOrbit,” as used herein, is a standard term used in the field ofsatellite communications to denote a satellite orbit around the planetEarth with an altitude of approximately 35786 km (22240 miles) and withan orbital period equal to approximately 24 hours (average rotation timeof the Earth). A geosynchronous satellite has an orbit synchronized withthe rotation of the planet Earth and a non-zero orbital inclination inreference to the equatorial plane of the Earth. To an observer on theground, a geosynchronous satellite will appear to trace an analemma(depicted as a FIG. 8) in the sky.

Input—The term “input,” as used herein, is used to denote any deviceused to receive input from a user or a system. Some non-limitingexamples of input devices are: a keyboard, a microphone, a computermouse, a wireless signal communication, a game engine, and an electronicwriting device, wherein the electronic writing device permits a user towrite notes and to draw doodles on a pad to be transferred to a computerby use of a special electronic ball point pen.

Instruction means—The term “instruction means” when used as a noun withrespect to this invention generally indicates a set of operations to beperformed on a computer, and may represent pieces of a whole program orindividual, separable, software (or hardware) modules. Non-limitingexamples of “means” include computer program code (source or objectcode) and “hard-coded” electronics. The “means” may be stored in thememory of a computer or on a computer readable medium. In some cases,however, the term “means” refers to a class of device used to perform anoperation, and thus the applicant intends to encompass within thislanguage any structure presently existing or developed in the futurethat performs the same operation.

Multiplexer—The term “Multiplexer,” as used herein, is a standard termused in the fields of electronics, telecommunications, signalprocessing, digital circuits design, and computer networks to denote aprocess where multiple input signals, such as analog message signals ordigital data streams, are combined into one output signal over a sharedmedium. The aim of a multiplexer is to share an expensive resource, suchas a transponder channel or a wire, among multiple input signals. As anexample, in telecommunications, several telephone calls (multiple inputsignals) may be transferred using one wire (single output signal). Incontrast, an electronic multiplexer can be considered as a multipleinput, single-output switch. The two most basic forms of multiplexingare time-division multiplexing (TDM) and frequency-division multiplexing(FDM), where FDM requires modulation of each signal. Generally, amultiplexer is often used on a transmitting side of a communicationsystem with a complementary demultiplexer on the receiving side of thecommunication system.

MUX—An acronym for “Multiplexer.” The term “MUX,” as used herein, is astandard term used in the fields of electronics, telecommunications,signal processing, digital circuits design, and computer networks todenote a Multiplexer that allows multiple input signals to be combinedinto one output signal over a shared medium.

On-line—The term “on-line,” as used herein, is a standard term used todenote “under the control of a central computer,” as in a manufacturingprocess or an experiment. On-line also means to be connected to acomputer or computer network, or to be accessible via a computer orcomputer network.

Operation of downloading, at the downlink segment, the transformed WFMsignals transmitted from the satellite segment—The term “operation ofdownloading, at the downlink segment, the transformed WFM signalstransmitted from the satellite segment,” as used herein, is a standardterm used to denote the process by which a signal (in this case atransformed WFM signal) is downloaded from the satellite and is receivedand processed at the downlink segment. The “operation of downloading, atthe downlink segment, the transformed WFM signals transmitted from thesatellite segment” comprises the operations of:

-   -   receiving, at a user end of downlink segment, the frequency        translated WFM signals from the transponders; and    -   amplifying the received frequency translated WFM signals from        the transponders.

Operation of processing, at the downlink segment, the downloadedtransformed WFM signals to a base-band frequency resulting in base-bandfrequency WFM signals—The term “operation of processing, at the downlinksegment, the downloaded transformed WFM signals to a base-band frequencyresulting in base-band frequency WFM signals,” as used herein, is astandard term used to denote the process by which a signal (in this casea downloaded transformed WFM signal) is frequency down-converted from asatellite amplified frequency translated WFM signal to a common IF orbase-band frequency, resulting in base-band frequency WFM signal.

Operation of transforming a WFM signal to satellite frequency band—Theterm “operation of transforming a WFM signal to satellite frequencyband,” as used herein, is a standard term used to denote the process bywhich a signal (in this case a WFM signal) is up-converted, at theuplink segment, into a signal in the satellite frequency band. Theoperation of transforming the WFM signals to a satellite frequency bandcomprises the operations of: frequency up-converting the outputwavefront multiplexed signals to distinct frequency carriers withinfrequency bands for satellite communications; amplifying frequencyup-converted wavefront signals; and

-   -   frequency multiplexing amplified wavefront signals by utilizing        an output multiplexer at the satellite frequency band.

Operation of transmitting, at the satellite segment, the transformed WFMsignals to a downlink segment—The term “operation of transmitting, atthe satellite segment, the transformed WFM signals to a downlinksegment,” as used herein, is a standard term used to denote the processby which a signal (in this case a transformed WFM signal) is transmittedthrough the satellite segment towards a downlink segment. The “operationof transmitting, at the satellite segment, the transformed WFM signalsto a downlink segment” comprises the operations of:

-   -   receiving in a satellite the transformed wavefront multiplexed        signals; translating the carrier    -   frequencies of the transformed wavefront multiplexed signals;        and    -   amplifying and transmitting the frequency translated wavefront        multiplexed signals through the satellite transponders toward        the user end of downlink segments, wherein each frequency        translated wavefront multiplexed signal is amplified and        transmitted through its own individual and independent        transponder, whereby all designated transponders in the        satellite are being utilized to transmit frequency translated        wavefront multiplexed signals, thereby utilizing all available        space assets of the satellite.

Real-time—The term “real-time,” as used herein, is a standard term usedto relate to computer systems that update information, or perform atask, at the same rate as they receive data.

Recording media—The term “recording media,” as used herein, denotes anymedia used to store information about an object or a scene. Somenon-limiting examples of recording media are: a video film, a videorecording tape, an audio recording tape, an audio cassette, a videocassette, a video home system (VHS) tape, an audio track, a Compact Disk(CD), a Digital Versatile Disk/Digital Video Disk (DVD), a floppy disk,a removable hard drive, a digital camera, a solid-state recording media,a printed picture, a scanned document, a magnetic tape, and a faxeddocument.

User—The term “user,” as used herein, denotes a person utilizing themethod for automatically extracting geospatial features frommulti-spectral imagery.

Wavefront-Multiplexer—The term “Wavefront-Multiplexer,” as used herein,is not a standard term used in the fields of telecommunications,electronics, signal processing, digital circuits design, or computernetworks. Instead, the term Wavefront-Multiplexer is used to denote aspecialized signal processing transform based on a variation from thestandard multiplexer known by one skilled in the art, whereas amultiplexer combines multiple inputs into a single output, theWavefront-Multiplexer allows multiple inputs to be combined intomultiple outputs, such that each output is comprised of a unique linearcombination of all the inputs and such that the outputs from theWavefront-Multiplexer are orthogonal to one another. TheWavefront-Multiplexer is a multiple-input/multiple-output (MIMO)transform that has at least as many outputs as there exist inputsconnected to the wavefront-multiplexer. The Wavefront-Multiplexerperforms an orthogonal functional transformation from a spatial-domainrepresentation of the inputs to a wavefront-domain representation of theinputs, wherein a necessary and sufficient condition of theWavefront-Multiplexer transform is that the Wavefront-Multiplexertransform has a realizable unique inverse.

WFM—An acronym for “Wavefront-Multiplexer.” The term “WFM,” as usedherein, is a non-standard term used to denote a wavefront-multiplexer,wherein the Wavefront-Multiplexer is a specialized signal processingtransform based on a variation from the standard multiplexer, whereas amultiplexer combines multiple inputs into a single output, theWavefront-Multiplexer allows multiple inputs to be combined intomultiple outputs, such that each output is comprised of a unique linearcombination of all the inputs and such that the outputs from theWavefront-Multiplexer are orthogonal to one another.

Wavefront-De-Multiplexer—The term “Wavefront-De-Multiplexer,” as usedherein, is not a standard term used in the fields of telecommunications,electronics, signal processing, digital circuits design, or computernetworks. Instead, the term wavefront-de-multiplexer is used to denote aspecialized signal processing transform based on a variation from thestandard de-multiplexer known by one skilled in the art, whereas ademultiplexer separates or splits a single input signal, that carriesmultiple individual signals within, into multiple output signalscorresponding to the individual signals carried by the single inputsignal, the wavefront-de-multiplexer separates multiple inputs, thateach carry a unique mixture of individual signals, into multipleoutputs, such that each output corresponds to one of the individualsignals carried by the multiple inputs. The wavefront-de-multiplexer isa multiple-input/multiple-output (MIMO) transform that performs anorthogonal functional transformation from a wavefront-domainrepresentation of signals to a spatial-domain representation of signals.The wavefront-de-multiplexer is a complementary transform to thewavefront-multiplexer, wherein the wavefront-de-multiplexer is oftenused on a receiver side of a communication system with a complementaryWavefront-Multiplexer on the transmitting side of the communicationsystem. The aim of a wavefront-de-multiplexer is to extract the originaltransmitted signals on a receiver side of a transmission system.

WFDM—An acronym for “Wavefront-De-Multiplexer.” The term “WFDM,” as usedherein, is a non-standard term used to denote aWavefront-De-Multiplexer, wherein the wavefront-de-multiplexer is aspecialized signal processing transform based on a variation from thestandard de-multiplexer, whereas a de-multiplexer separates or splits asingle input signal, that carries multiple individual signals within,into multiple output signals corresponding to the individual signalscarried by the single input signal, the wavefront-de-multiplexerseparates multiple inputs, that each carry a unique mixture ofindividual signals, into multiple outputs, such that each outputcorresponds to one of the individual signals carried by the multipleinputs.

(2) Overview

In the following detailed description, numerous specific details are setforth in order to provide a more thorough understanding of the presentinvention. However, it will be apparent to one skilled in the art thatthe present invention may be practiced without necessarily being limitedto these specific details. In other instances, well-known structures anddevices are shown in block diagram form, rather than in detail, in orderto avoid obscuring the present invention.

Some portions of the detailed description are presented in terms of asequence of events and symbolic representations of operations on databits within an electronic memory. These sequential descriptions andrepresentations are the means used by artisans to most effectivelyconvey the substance of their work to other artisans. The sequentialsteps and operations are generally those requiring physicalmanipulations of physical quantities. Usually, though not necessarily,these quantities take the form of electrical or magnetic signals capableof being stored, transferred, combined, compared, and otherwisemanipulated. It has proven convenient at times, principally for reasonsof common usage, to refer to these signals by terms such as bits,pixels, values, data, video frames, audio signals, elements, files,digital signal streams, and coefficients.

It is to be understood, that all of these, and similar terms, are to beassociated with the appropriate physical quantities, and are merelyconvenient labels applied to these quantities. Unless specificallystated otherwise as apparent from the following discussions, it isappreciated that throughout the present disclosure, discussionsutilizing terms such as “acquiring,” “amplifying,” “augmenting,”“calculating,” “communicating,” “controlling,” “converting,”“determining,” “displaying” “downloading,” “extracting,” “inputting,”“interacting,” “interfacing,” “mapping,” “matching,” “modeling,”“obtaining,” “outputting,” “performing,” “processing,” “receiving,”“recognizing,” “recovering,” “separating,” “tracking,” “transforming,”“transmitting,” “translating,” or “uploading,” refer to the action andprocesses of a computer system, or similar electronic device thatmanipulates and transforms data represented as physical (electronic)quantities within the system's registers and memories into other datasimilarly represented as physical quantities within the computer systemmemories or registers or other such information storage, transmission,or display devices. Furthermore, the processes presented herein are notinherently related to any particular processor, processor component,computer, software, or other apparatus.

(3) Physical Embodiments of the Present Invention

The present invention has two principal “physical” embodiments. Thefirst is a system for dynamically combining power from a plurality ofpropagation channels (transponders) in order to improve power levels oftransmitted signals. In doing so, the dynamic power allocation isimplemented through the transmitter segment (ground end of uplinksegment) without affecting the receiver segment (user end of downlinksegment) and the propagation segment (space segment), and withoutmodifying configuration of propagation apparatus and propagationchannels (satellite and transponders in the space segment). Such asystem is typically but not limited to a computer system operatingsoftware in the form of a “hard coded” instruction set.

This system may also be specially constructed, as anapplication-specific integrated circuit (ASIC), or as a readilyreconfigurable device such as a field-programmable gate array (FPGA).

The second physical embodiment is a method, typically in the form ofsoftware, operated using a data processing system (computer).

A block diagram depicting the components of a computer system used inthe present invention is provided in FIG. 1. The data processing system100 comprises an input 102 for receiving a plurality of input signalscomprising digital signals, analog signals, mixed analog and digitalsignals, and a plurality of digital signal streams. The input 102 mayalso be configured for receiving a user's input or an operator's inputfrom another input device such as a microphone, keyboard, drawing pads,or a mouse, in order for the operator (user) to dynamically allocateequivalent transponder powers according to continuously changing marketdemands by dynamically including change of relative input powers intoratios of mixtures of the input digital signal streams. Note that theinput 102 may include multiple “ports” for receiving data and userinput, and may also be configured to receive information from remotedatabases using wired or wireless connections. The output 104 isconnected with the processor for providing output to the user(operator), on a video display but also possibly through audio orkinesthetic signals (e.g., through pinching, vibrations, heat, etc.).Output may also be provided to other devices or other programs, e.g. toother software modules, for use therein, possibly serving as a wired orwireless gateway to external databases or other processing devices. Theinput 102 and the output 104 are both coupled with a processor 106,which may be a general-purpose computer processor or a specializedprocessor designed specifically for use with the present invention. Theprocessor 106 is coupled with a memory 108 to permit storage of data andsoftware to be manipulated by commands to the processor. Typicalmanifestations of the data processing system 100 may be incorporatedinto a ground end of an uplink segment, a program aggregation facilityfor a DBS service, a user end uplink segment, vehicles, cellular phones,portable digital assistants, and computers. It should be recognized bythose skilled in the art that multiple processors may also be used andthat the operations of the invention can be distributed across them.

(4) Detailed Description of the Elements

1) Embodiment of the Invention for a Dynamic Communication System

A detailed description of an embodiment of the present invention ispresented schematically in a diagram in FIG. 2. FIG. 2 illustrates adynamic communication system suitable for dynamically combining powerfrom a plurality of propagation channels through a transmitter segment200 without affecting the receiver segment 204 and propagation segment202. In this detailed embodiment, the blocks in the diagram representthe functionality of the system of the present invention. At the start,the system inputs (receives) a plurality of signals 206 to betransmitted, where the terms A1, A2, A3, and A4 in FIG. 2 denote anon-limiting example of four input signals 206 to be transmitted by thedynamic communication system. Next, the system transforms the inputsignals 206 into wavefront multiplexed signals 208 (WFM signals) byperforming a Wavefront-Multiplexing transform 210 (WFM transform), wherethe terms WFM1, WFM2, WFM3, and WFM4 in FIG. 2 denote the four wavefrontmultiplexed signals 208 generated by the Wavefront Multiplexingtransform 210. Then, the system transmits the WFM signals 208 over atransmission medium 212 through propagation channels 214, wherein thereexist at least as many propagation channels 214 as there exist WFMsignals 208, and where each WFM signal 208 is transmitted over its ownpropagation channel 214. In this embodiment, the propagation segment 202comprises a transmission medium 212 and a plurality of propagationchannels 214, along with a propagation apparatus (such as a satellite).Some non-limiting and non-exhaustive examples of a propagation mediumcomprise air, water, outer space, fiber optical lines, sound waves,radio waves, sonar, wires, light, and radar.

Next, the system receives, at the receiver segment 204, the transmittedWFM signals 216 from the propagation channels 214, where the termsWFM^(Λ) 1, WFM^(Λ) 2, WFM^(Λ) 3, and WFM^(Λ) 4 in FIG. 2 denote the fourtransmitted WFM signals 216 received from the propagation channels.These transmitted WFM signals 216 (WFMA1, WFMA2, WFMA3, and WFMA4) havebeen modified during the transmission in the propagation segment 204 andhave unbalanced amplitudes, unbalanced phases, and/or unbalancedtime-delays with respect to the initial WFM signals 208 (WFM1, WFM2,WFM3, and WFM4) originally transmitted, in addition to having dynamicdifferential propagation effects due to the transmission medium.Therefore, the system performs, at the receiver segment 204, adaptiveequalization 218 on the received WFM signals 216 (WFMA1, WFMA2, WFMA3,and WFMA4) in order to account for the propagation channel effectscomprising dynamic differential propagation effects due to thetransmission medium 212 and static differential propagation effectscomprising unbalanced amplitudes, unbalanced phases, and/or unbalancedtime-delays between the received WFM signals 216 (WFMA1, WFMA2, WFMA3,and WFMA4) and the WFM signals 208 (WFM1, WFM2, WFM3, and WFM4)outputted by the WFM transform 210. During the adaptive equalizationprocess, the adaptive equalizer 218 generates equalized WFM signals 220,where the terms EWFMA1, EWFMA2, EWFMA3, and EWFMA4 in FIG. 2 denote theequalized WFM signals 220 generated by the adaptive equalizer 218.

Once the propagation channel effects from the propagation segment havebeen reversed by the adaptive equalizer 218, the system separates theequalized WFM signals 220 into individual spatial-domain signals 206 byperforming a Wavefront-De-Multiplexing transform 222 (WFDM transform),where the terms A1, A2, A3, and A4 in FIG. 2 denote the individualspatial-domain signals 206 recuperated by the receiver segment 204, suchthat the recuperated spatial domain signals correspond to the originalspatial domain input signals 206 initially transmitted by thetransmitter segment 200. Next, the system outputs the individualspatial-domain signals 206.

During the adaptive equalization process 218 performed at the receiversegment 204, this embodiment of the invention connects a control signal224 to a WFM input port denoted by the term A1. This WFM input portconnected to a control signal 224 at the transmitter segment 200 has acorresponding WFDM controlled output port 226 at the receiver segment204. The WFDM controlled output port 226 is used as a diagnostic portwhere a cost function is used to measure the difference between thecontrolled input port 224 and its corresponding diagnostic port 226.Then, the system uses an optimization processor and several compensationprocessors 228 (such as amplitude, phase, and time-delay compensationprocessors) to generate compensation signals 230 that compensate for thepropagation channel effects from the propagation segment 202 and whichare used to adjust the adaptive equalizer 218 in order to minimize thecost function. Adaptive equalization is reached when the cost functionis minimal and the cost function can no longer be reduced any further.

An embodiment of the invention utilizes two separated areas oftechnology to equivalently achieve power combining and providing betterthroughput and availability of broadcasted signals to DBS groundsubscribers. These two technological areas are: wave-front multiplexingand adaptive equalization, and compensation among multiple signal paths.

II) Wavefront Multiplexing

A detailed description of Wavefront-Multiplexing is presented. AWavefront-Multiplexer or Wavefront Multiplexing is a specialized signalprocessing transform based on a variation from the standard multiplexerknown by one skilled in the art. Whereas a standard multiplexer combinesmultiple inputs into a single output, the Wavefront-Multiplexer allowsmultiple inputs to be combined into multiple outputs, such that eachoutput is comprised of a unique linear combination of all the inputs andsuch that the outputs from the Wavefront-Multiplexer are orthogonal toone another. Therefore, the Wavefront-Multiplexer (WFM) is amultiple-input/multiple-output (MIMO) transform that has at least asmany outputs as there exist inputs connected to thewavefront-multiplexer. The Wavefront-Multiplexer performs an orthogonalfunctional transformation from a spatial-domain representation of theinputs (such as the terms A1, A2, A3, and A4 in FIG. 2 denoted byelement 206) to a wavefront-domain representation of the inputs (such asthe terms WFM1, WFM2, WFM3, and WFM4 in FIG. 2 denoted by element 208).A necessary and sufficient condition of the Wavefront-Multiplexertransform is that the Wavefront-Multiplexer transform has a realizableunique inverse.

A complementary transform to the Wavefront-Multiplexer is theWavefront-De-Multiplexer. The Wavefront-De-Multiplexer is often used ona receiver side of a communication system with a complementaryWavefront-Multiplexer on the transmitting side of the communicationsystem. The aim of a Wavefront-De-Multiplexer is to extract the originaltransmitted signals on a receiver side of a transmission system.Generally, Wavefront-De-Multiplexer is used to denote a specializedsignal processing transform based on a variation from the standardDe-Multiplexer known by one skilled in the art. Whereas a De-Multiplexerseparates or splits a single input signal that carries multipleindividual signals within into multiple output signals corresponding tothe individual signals carried by the single input signal, theWavefront-De-Multiplexer separates multiple inputs, that each carry aunique mixture of individual signals, into multiple outputs, such thateach output corresponds to one of the individual signals carried by themultiple inputs. The Wavefront-De-Multiplexer is amultiple-input/multiple-output (MIMO) transform that performs anorthogonal functional transformation from a wavefront-domainrepresentation of signals to a spatial-domain representation of signals.

For illustrative purposes, the concepts of Wavefront Multiplexing andWavefront De-Multiplexing are graphically illustrated in FIG. 3.Generally, the operations of the Wavefront-Multiplexer andDe-Multiplexer can be graphically visualized by the use of twodimensional lenses, where each lens consists of two surfaces that areconstructed as follows: (a) the left surface of a lens (left edge ofeach lens 300 a and 300 b) is a segment of a circle 304 centered at themiddle of the right surface of the lens (elements 302 a and 302 b) witha radius of R, and (b) the right surface of a lens (right edge of eachlens 302 a and 302 b) is a segment of a circle 306 centered at themiddle of the left surface (elements 300 a and 300 b) with a radius ofR. The lens on the right of FIG. 3 (formed by the lens surfaces 300 band 302 b) is the mechanisms for Wavefront Multiplexing, while the lenson the left (formed by the lens surfaces 300 a and 302 a) is themechanisms for Wavefront De-Multiplexing.

In order to graphically visualize the functionality of these wavefronttransforms, the two lenses representing the Wavefront Multiplexing(WFM)/De-Multiplexing (WFDM) pair are connected by eight identicaloptical fibers 308 that act as propagation channels. On one end, theeight optical fibers are connected evenly distributed on the circularsurface of the right edge 302 a of the left lens corresponding to theWFDM lens (elements 300 a and 302 a). On the other end, the eightoptical fibers are connected evenly distributed on the circular surfaceof the left edge 300 b of the right lens corresponding to the WFM lens(elements 300 b and 302 b).

The functionality of the WFDM is illustrated as follows: Two signalsources denoted by 310 (source A) and 312 (source B) are connected tothe inputs of the right lens 300 a of the WFDM, where the source A 310is above the center of the circular surface of the opposite edge of thelens 302 a and source B 312 is below the center of the circular surfaceof the opposite edge of the lens 302 a. Source B 312, as shown,generates a circular wavefront centered at the B port 314 (the circularwavefront 314 is similar to concentric circles or waves generated bythrowing a pebble into a peaceful lake). The circular wavefront 314originated by the source B 312 is picked up by the eight optical fibers308, which are connected and evenly distributed on the circular surfaceof the right edge 302 a of the left lens (WFDM). However, the opticalfibers do not pick up the circular wavefront at the same time, but eachoptical fiber receives the wavefront in a sequential manner (after sometime delay). As such, the input for optical fiber number 8 senses thewavefront first while the input for the optical fiber number 1 receivesthe wavefront the last. In a similar manner, the circular wavefrontsgenerated by source A 310 will be sensed by the optical fibers on areverse sequence order, such that fiber number 1 will sense thewavefront generated from source A 310 first, while fiber number 8 willbe the last fiber to sense the wavefront from source A 310. As a result,there are two different and simultaneous wavefronts propagating throughthe eight fibers at the same time but at different time delays and offphase from each other, one from source A 310 and the other from source B312. Therefore, the wavefront 314 generated by source B 312 is travelingthrough each one of the eight fibers at different moments in time alongwith the wavefront generated by source A 310, such that both wavefrontsare intermixed with each other through time delays and phase delayswithin each optical fiber, and such that there are eight differentrepresentations of each wavefront generated by a source travelingthrough the fibers at any point in time (similar in nature to a standardDeMultiplexer).

The functionality of the WFM, denoted by the lens on the right (300 band 302 b) in FIG. 3, is illustrated as follows: The lens on the rightin FIG. 3 is designed to have eight optical fiber inputs 308 connectedto the left edge 300 b of the right lens, and two outputs 310 _(A) and312 _(A) connected to the right circular surface 302 b of the rightlens. The two-dimensional lens (300 b and 302 b) is architected to focustwo unique circular wavefronts received from the left surface to twounique “sinks” 310 _(A) and 312 _(A) (denoted by elements A′ and B′) onthe right surface 302B. One of the incoming waveforms will be focused tothe sink port A′ 310 _(A) forming a peak at sink A′ 310 _(A) with a nullat sink B′ 312 _(A), while the other incoming wavefront 314A will befocused to the sink port B′ 312A forming a peak at sink B′ 312 _(Λ) witha null at sink A′ 310 _(Λ).

When the fibers in the bundle are identical, with equal amplitudeattenuations and equal propagation delays through all the eight fibers(i.e., no propagation channel effects), the source A 310 will betransported to sink A′ 310 _(A) while source B 312 will be transportedto sink B′ 312 _(A). However, usually the fibers in the bundle will notbe identical in amplitude attenuations and propagation delays throughout all eight fibers due to environment changes or aging, thus creatingdisparate propagation effects. As a result, the source A 310 will notonly be transported to sink A′ 310 _(A) but also with leakage into sinkB′ 312 _(A). In a similar manner, source B 312 will not only bedelivered to the intended destination of sink B′ 312 ^(A). but also tothe unintended destination of sink A′ 310 _(A).

Therefore, in order to be able to recuperate the original signals beingtransmitted over the optical fibers (propagation channels), adaptivechannel equalization must be performed prior to separating theintermixed wavefront multiplexed signals in the fibers (propagationchannels) in order to eliminate the propagation channel effects from theoptical fibers and to avoid leakage from one signal into the sink of theother signal.

Reversing the flow of the signals in FIG. 3 illustrates thefunctionality of the WFM transformation, where the functionality of theWFM is represented by the combination of lens edges 300 b and 302 b. Thereverse flow of signals traveling from right to left (through theoptical fibers 308) is generated by two sources A′ 310 ^(A) and B′ 312^(A) on the right side of FIG. 3. As a result of WFM as illustrated inFIG. 3, each optical fiber 308 (or propagation channel) carries the twoinput signals, generated by source A′ 310 _(A) and source B′ 312 _(A)respectively, in a unique linear combination. The eight optical fibers308 carry eight intermixed wavefront multiplexed signal combinations ofthe two input signals, where the intermixed WFM signal combinationscorrespond to unique and orthogonal linear combinations of the two inputsignals generated by the two sources A′ 310 _(A) and B′ 312 _(A). Next,the propagation channel effects among the different optical fibers mustbe dynamically equalized (by adaptive equalization) at the left side(receiver segment) using cost minimization algorithms prior toseparating the intermixed WFM signals by using the WFDM, where thefunctionality of the WFDM is represented by the combination of edges ofthe left lens 300 a and 302 a. Once the propagation channel effects fromthe optical fibers are eliminated, the two original signals from theright side sources A′ 310 _(Λ) and B′ 312 _(Λ) are then transformed viaWFDM into the two recuperated input signals.

Mathematically, the Wavefront Multiplexing and De-Multiplexer operationis an orthogonal functional manipulation or transformation, and it maybe implemented many ways. The transformation is not in between the timeand frequency domains, but is an orthogonal transformation between thespatial domain and the wave-front domain.

The Wavefront Multiplexing transformation is expressed by a linearequation as follows:

Y=WFM*X,  (1)

where

X denotes the input vectors,

Y denotes the output vector, and

WFM denotes the functional transformation matrix.

In addition, the wavefront transformation features the characteristicthat the WFT is orthogonal to itself, such that

WFM*WFM=I  (2)

A non-limiting example of an orthogonal transformation matrix used toimplement an embodiment of the Wavefront Multiplexing transform ispresented below. This non-limiting example of a WFM transform isimplemented by an analogue 4-to-4 Butler Matrix (BM) at the Ku band. Twoexamples of the vector weightings 400 a, 400 b, by phase rotation only,are illustrated in FIG. 4, where the WFM operation, WFM, is a 4×4matrix, with 4 row matrices as follows:

[W11, W12, W13, W14]=[exp(j012), exp(j012), exp(j013), exp(j014)], [W21,W22, W23, W24]=[exp(j021), exp(j022), exp(j023), exp(j024)], [W31, W32,W33, W34]=[exp(j031), exp(j032), exp(j033), exp(j034)], [W41, W42, W43,W44]=[exp(j041), exp(j042), exp(j043), exp(j044)],

Since the WFM operation, WFM, is a linear operation, it may beimplemented as 8×2-to-8×2 or 2×2-to-2×2 BMs at baseband. In addition toimplementing a WFM transform using a Butler Matrix, a plurality ofspecific WFM matrices can be generated using Fourier transform pairs orHartley transform pairs when working in the digital domain.

III) Embodiment of the Invention for Satellite Communications

Another embodiment of the invention (using WFM techniques) can be usedfor satellite communications, including DBS applications, in order toallow N individual signal streams from a given uplink ground station(transmitter segment) to go through M independent transponders (orpropagation channels) on a satellite (propagation apparatus). Then, thereceiving downlink ground stations or subscriber terminals (receiversegment) can recover the individual signal streams faithfully by usingWavefront De-Multiplexing (WFDM) and additional signal processingprocesses, such adaptive equalization to remove propagation channeleffects, under the constraint that there exist at least as many numberof transponders, M, as there exist individual signal streams, N, beingtransmitted. One of the many possible applications of this WFM techniqueis the effective power combining, or Equivalent Isotropic Radiated Power(EIRP) combining, from various transponders in the same satellite orfrom various transponders in different satellites. The power combiningcorresponds to a dynamic power allocation implemented through the uplinkstation (transmitter segment) without affecting the receiving groundstations (receiver segment) and without affecting the satelliteconfiguration (propagation segment).

As a result of WFM as previously illustrated in FIG. 3, each transponder(or channel) carries all the signal streams in a unique linearcombination. The M transponders correspond to M different and orthogonallinear combinations of the N signals streams. Then, the propagationchannel effects among the different transponders must be dynamicallyequalized (by adaptive equalization) at the received ground station(receiver segment) using cost minimization algorithms. The M equalizedreceived channels are then transformed via WFDM into the N recuperatedsignal streams.

FIG. 5 provides schematically in a functional block diagram anembodiment of the invention for a dynamic satellite communication systemsuitable for dynamically combining power from a plurality of satellitetransponders in order to improve the power levels of the transmittedsignals. In this detailed embodiment, the blocks in the diagramrepresent the functionality of the system of the present invention.Furthermore, the schematics illustrated in FIG. 5 simply reflect anexample of a non-limiting and non-exhaustive combination of inputsignals, satellites, satellite transponders, and control signals thatmay be used with an embodiment of this invention. These signals'examples (illustrated in FIG. 5) are provided in order to assist withthe description of the functionality of this embodiment of the inventionand these signals' examples represent only a non-limiting illustrationof one of many combinations of the input signals, satellites, satellitetransponders, and control signals that may be used with the presentinvention.

FIG. 5 depicts two simplified functional block diagrams of two satellitebased direct broadcasting systems (DBS). The top panel 500 depicts aconventional DBS system as generally used in the art of satellitecommunication, including a transmitter segment comprising a grounduplink segment 502 a, a propagation segment comprising one satellitewith a plurality of satellite transponders 504 a, and a receiver segmentcomprising a DBS subscriber terminal 506 a. The bottom panel 508 depictsan embodiment of the present invention for a dynamic satellite DBScommunication system using a WFM transform 510 in the ground uplinksegment 502 b of the dynamic satellite DBS system. Both of these DBSsystems, the conventional DBS system 500 and the WFM DBS system 508,comprise: a transmitter segment comprising an uplink ground station, 502a and 502 b, illustrated on the left side of FIG. 5; a propagationsegment comprising one satellite with four satellite transpondersavailable for transmitting signals, 504 a and 504 b, illustrated on themiddle of FIG. 5; and a receiver segment comprising a least one DBSsubscriber terminal, 506 a and 506 b, illustrated on the right side ofFIG. 5.

III-i) Conventional DBS Satellite System

In this particular conventional DBS system 500, there are four satellitetransponders 504 a available to transmit signals via a satellite. Assuch, the ground uplink segment 502 a is capable of transmitting fourinput signals 516 a (denoted by the terms d1, d2, d3, and d4)simultaneously to the four available satellite transponders. However, inthis particular example, there are only two input streams of digitalsignals, represented by term S7 (denoted by element 512) and by term S8(denoted by element 514), to be broadcasted via the DBS system 500 tovarious users 506 a. Therefore, two of the inputs 516 a of the grounduplink segment (referring to terms d3 and d4) are empty (not connectedto input signals) or connected to ground signals 518 a or zero valuesignals (for illustration purposes). Additionally, the other two inputs516 a of the ground uplink segment (referring to terms d1 and d2) areconnected to the two input signal streams being broadcasted, where inputsignal stream 512 (term S7) is connected to uplink segment input d1 andinput signal stream 514 (term S8) is connected to uplink segment inputd2, respectively.

The two input digital streams, 512 and 514, at the uplink station 502 a,are transformed to a satellite frequency band by performing theoperations of: frequency up-converting 520 a the input digital streams,512 and 514, to two different carrier frequencies within the Kusatellite frequency band; and amplifying and frequency multiplexing 524a the two frequency up-converted input signals 522 a by utilizing anoutput multiplexer at the Ku satellite frequency band. Next, the twotransformed Ku band signals 526 a are uploaded to the Ku broadcastingsatellite via an uplink ground antenna in an uploading facility.

On the satellite, the received Ku band signals 526 a go through twoseparated satellite transponders 504 a, individually and independently,before they are ready for broadcasting to various subscriber terminals506 a. The current conventional DBS satellite systems, such as 500, onlyneed two of the available satellite transponders to broadcast the twoinput digital streams, 512 and 514, and thus under utilize the rest ofthe available space assets, as shown. Therefore, the conventional DBSsatellite system 500 only occupies 50% of the available space assets and50% of the space assets are wasted (referring to the two unusedsatellite transponders that are available for broadcasting but that arenot being utilized during the broadcast by the current conventional DBSsatellite systems).

At the subscriber terminals 506 a, the proper transponder channels areselected, the desired signals are amplified, filtered, synchronized andde-modulated to recover the intended digital data streams 528 a and 530a (denoted by terms S7′ and S8′, respectively) for further processingprior to providing the processed signals to TV displays.

III-ii) Embodiment of Invention for a Dynamic DBS Satellite System UsingWFM Transformation

In contrast with the current conventional DBS satellite systems, thisembodiment of the invention for a dynamic DBS satellite system, in thebottom panel 508 of FIG. 5, utilizes 100% of the space assets availablefor transmission. That is, the wavefront multiplexed DBS systemtransmits both input signal streams, 512 and 514, through all theavailable satellite transponders 504 b, such that all four satellitetransponders are used to broadcast the input signal streams.

Similarly to the conventional DBS satellite system 500, this WFM DBSsatellite system 508 has four satellite transponders 504 b available totransmit signals via a satellite. As such, the ground uplink segment 502b is capable of transmitting four input signals 516 b (denoted by theterms d1A, d2 ^(A) d3A, and d4A) simultaneously to the four availablesatellite transponders. Equally to the conventional DBS satellitesystem, there are only two input streams of digital signals at theground uplink segment 502 b, represented by term S7 (denoted by element512) and by term S8 (denoted by element 514), to be broadcasted via theWFM DBS satellite system 508 to various subscriber terminals 506 b(users or receiver segments). Therefore, two of the inputs, 518 b and519 b, to the WFM transform 510 at the ground uplink segment 502 b ofthe invention, are empty (not connected to input signals) or connectedto ground signals or zero value signals (for illustration purposes), andthe other two inputs of the WFM transform 510 are connected to the twoinput signal streams being broadcasted, 512 (term S7) and 514 (term S8),respectively.

In contrast with current DBS satellite systems, this embodiment of theinvention transforms the two input digital streams, 512 and 514, at theuplink station 502 b, into four simultaneous WFM digital streams 516 b(denoted by terms d1 ^(A) d2A, d3 ^(A) and d4A) by performing wavefrontmultiplexing, prior to frequency up-converting the input signals to fourdifferent carrier frequencies in the Ku frequency band. Next, the fourWFM digital streams 516 b (denoted by terms d1 ^(A) d2 ^(A) d3A, andd4A), at the uplink station 502 b, are transformed to a satellitefrequency band by performing the operations of: frequency up-converting520 b the four WFM digital streams 516 b, to four different carrierfrequencies within the Ku satellite frequency band; and amplifying andfrequency multiplexing 524 b the four frequency up-converted WFM signals522 a by utilizing an output multiplexer at the Ku satellite frequencyband. Next, the four transformed Ku band WFM signals 526 b are uploadedto the Ku broadcasting satellite via an uplink ground antenna in anuploading facility.

In this embodiment, the wavefront multiplexer (WFM) can be implementedat digital base-band in digital format, or by analogue devices such as a“Butler matrix.” Each of the four outputs 516 b from the WFM (denoted byterms d1 ^(A) d2A, d3 ^(A) and d4A), is a linear combination of bothinput signals 512 and 514, and each WFM output features a differentcombination of the input signals than the combinations stored on theother WFM outputs. Furthermore, the four WFM outputs are orthogonal toone another.

On the satellite, the received Ku band WFM signals 526 b go through thefour separated satellite transponders 504 b, individually andindependently, before they are ready for broadcasting to varioussubscriber terminals 506 b. The WFM DBS satellite system 508 uses all ofthe available satellite transponders (uses all four transponders) tobroadcast the two input digital streams, 512 and 514 and, therefore,utilize 100% of the available space assets. This is to be contrastedwith the conventional DBS satellite system 500 which only occupies 50%of the available space assets (only uses two transponders fortransmission).

At the subscriber terminals 506 b, the four received wave-frontmultiplexed signals 532 at the four separated carrier frequencies areamplified before being frequency down converted to a common IF orbase-band. Next, the four down converted signals 534 are processedthrough a 4-to-4 wavefront de-multiplexer (WFDM) 536 to recover thedesired signals, which are amplified, filtered, synchronized andde-modulated to restore the intended digital data streams 528 b and 530b (denoted by terms S7′ and S8′, respectively) for further processingprior to providing the processed signals to TV displays.

In order to restore the original digital input data streams 512 and 514(denoted by terms S7 and S8), the amplitude, time-delays, and thephase-delays of the WFM transmitted signals 516 b must be kept constantamong the four paths connecting the four outputs of the WFM 516 b at theupload station 502 b and the four inputs 534 of the WFDM 536 of asubscriber's terminal 506 b. This constraint must be included in anyembodiment of the present invention since this is a necessary andsufficient condition to make the WFM DBS satellite system work.

Furthermore, this embodiment of the invention utilizes the informationderived from the WFDM at a user or subscriber's terminal together with aunique optimization processes to adaptively equalize the four pathsindividually (between WFM signals 516 b and WFDM input signals 534), ateach of the subscriber's terminals. The adaptive equalizationcompensates for path length of phase, time, and amplitude differencesamong various transponders and propagation effects. The channelcompensations are two folds: compensation for static difference ofunbalanced amplitudes, unbalanced phases, and unbalanced time-delaysamong the four transponders, and static propagation effects due to thetransmission medium; and compensation for dynamic differentialpropagation effects due to the transmission medium, such as rainprecipitation among the four paths (propagation channels). FIG. 6depicts a simplified functional block diagram of an embodiment of a WFMDBS satellite architecture, comprising the operational principles of anoptimization loop 600 at subscriber sites used to perform adaptiveequalization of propagation channel effects.

In a similar manner as the embodiment illustrated in FIG. 5, thisembodiment of a WFM DBS satellite system 608, in FIG. 6, has foursatellite transponders 604 available to transmit signals through asatellite, and as such, the ground uplink segment 602 is capable oftransmitting four input signals 616 (denoted by the terms d1, d2, d3,and d4) simultaneously to the four available satellite transponders 604.Initially, this embodiment transforms the two input digital streams, 612and 614, at the uplink station 602, into four simultaneous WFM digitalstreams 616 (denoted by terms d1, d2, d3, and d4) by performingwavefront multiplexing 610. Next, the four WFM digital streams 616, atthe ground uplink station 602, are transformed to a satellite frequencyband by performing the operations of: frequency up-converting 620 thefour WFM digital streams 616, to four different carrier frequencieswithin the Ku satellite frequency band; and amplifying and frequencymultiplexing 624 the four frequency up-converted WFM signals 622 byutilizing an output multiplexer at the Ku satellite frequency band.Next, the four transformed Ku band WFM signals 626 are uploaded to theKu broadcasting satellite.

On the satellite, the received Ku band WFM signals 626 go through thefour separated satellite transponders 604, individually andindependently, before they are ready for broadcasting to varioussubscriber terminals 606, thus utilizing 100% of the available spaceassets. At the subscriber terminals 606, the four received wave-frontmultiplexed signals 632 at the four separated carrier frequencies areamplified before being frequency down converted to a common IF orbase-band. Next, the four down converted signals 634 are processedthrough an adaptive equalizer 638 that compensates for unbalances onamplitude, phase, and time-delays. Then the equalized signals 640 arefeed to a 4-to-4 wavefront de-multiplexer (WFDM) 636 in order to recoverthe desired digital data streams 628 and 630 (denoted by terms S7′ andS8′, respectively).

At the ground uplink station 602, as a part of the adaptive equalization638, some of the inputs of the wave-front multiplexer are “grounded”(specifically the WFM inputs, 618 and 619, which are not connected to asignal to be transmitted). As a result, the outputs, 642 and 644, of theWFDM 640 in the user terminal 606 which correspond to the groundedinputs to the WFM, are connected to the optimization processor 600 to beused for diagnostic in the optimization loop. When adaptive equalizationis reached for all the amplitude, phase, and time-delays, at theequalized state, there are no signals detected at any of the diagnosticports, which for this particular embodiment correspond to the WFDMoutputs 642 and 644.

On the other hand, before the four paths are equalized, there aresignals leaking into the diagnostic ports corresponding to the WFDMoutputs 642 and 644. Therefore, the output powers from the diagnosticports (referring to the WFDM outputs 642 and 644) are used as anindication of “error” or as a “cost function.” In an embodiment of theinvention, the sum of the detected power levels from all the diagnosticpaths are used as the system “cost function” in an equalization loop. Asan optimization loop gradually and adaptively equalizes the fourpropagation paths, the “error” or the “cost” is continuously reduced.

An embodiment of the optimization scheme using WFM for “cost” functionmeasurement utilizes the following three parts for the equalizationmechanisms:

-   -   1. diagnostic circuit, which generates the values of the “cost”        function;    -   2. optimization processor (algorithm), which will calculate the        complex weights iteratively minimizing the values of cost        functions; and    -   3. compensation circuits, which implement the “complex        weighting” used to modify and adjust the amplitudes, phases, and        time-shifts of the WFM signals received at the subscriber        terminals.

The diagnostic circuit takes advantage of the nature of WFM and WFDM,utilizing the I/O ports to generate the cost function such that the whenthe paths are fully equalized the cost will become zero. The cost is apositive definite function, and can be defined in an ad hoc fashion(case-by-case), but usually it is defined such that when the M paths (Mtransponders or channels) are far away from being equalized, the cost islarge, and when the M paths (M propagation channels) are nearlyequalized, then the cost becomes small.

The optimization processor (algorithm) will dynamically measure thegradient of the cost functions, and it calculates the updated amplitude,phase, and time-shift compensations (i.e., the complex weights) for allthe paths accordingly. The optimization processor will iterativelycompensate the path differences of the propagation channels, reducingthe “cost” until the cost falls below a desired threshold.

The compensation circuits are the real implementation of the amplitude,phase, and time-shift changes on the M signal paths. The compensationcircuits can be implemented as a plurality of sets of phase shifters,time shifters, and amplitude attenuations, or I/Q with attenuations, inRF/IF analogue circuits. The compensation circuits may also beimplemented in digital domain as a part of digital beam forming (DBF)process.

In another embodiment of the invention, at least one output from theWFDM is used for “observables” measuring the error introduced by thedifferential drifts among the satellite-channels due to differentdynamic propagation effects. Then, the received power levels, in thediagnostic port, are used to derive the components of a cost function,which is “measurable” to calculate the dynamic compensation weightvector (CWV) for propagation effects. In this embodiment, the controlinput signal does not have to be a ground (zero value) signal.

In addition, when there exist as many input signals to be transmitted asthere exits available transponders in a satellite, a control inputsignal (to be used for the adaptive equalization) can be multiplexedtogether with one of the input signals into one of the WFM inputs. Inyet another embodiment of the invention, for slow varying environments,it is possible to feed back the observable information from the WFDM tothe uplink station for pre-compensation of the multi-satellitedifferential propagation effects.

III-iii) Example of Power Combining Aspect of the Invention

An advantage of this invention is an embodiment that involves a dynamicimprovement of radiated power over coverage areas by utilizingadditional transponders on a satellite or from different satellites thatare not being utilized at their full capacity and that have excessive(unused) radiated power available to be utilized, where the effectivedynamic power allocations are utilized and implemented through theground segment (transmitter segment or uplink segment) only, withoutaffecting the space segment (propagation segment) configuration. Forthis dynamic power allocation to be successful, the receiving-onlyterminals must “coherently combine” the radiated power from the varioustransponders, which is effectively accomplished by the optimization loopcomprised of the adaptive equalizer 638, the WFDM 636, and theoptimization processor 600.

In this embodiment, an operator, at a ground end of uplink segment 602or at a program aggregation facility for a DBS service, dynamicallyallocates equivalent transponder powers 604 according to continuouslychanging market demands by dynamically including change of relativeinput powers into ratios of mixtures of the input digital signalstreams, in order to improve radiated power of the input digital signalstreams being broadcasted without affecting the user end of downlinksegment 606 and the space segment, and without modifying satelliteconfiguration.

In general, the input intensity of the input signals streams (from theuplink station) are used to tap the output power of the varioustransponders from different satellites. The intensities of the inputsignal streams can be dynamically varied and they do not have to beequal. The following non-limiting example serves as an illustration of apower combining embodiment of the invention. This example assumes, forsimplicity, that the transponders are operated in a linear mode with anequal ERIP (radiated power) of 45 decibel watts (dBw), and with a singlecarrier per stream in each transponder. FIG. 7 is a table 700 showingthe results obtained using this example of a power combining embodimentof the invention.

This non-limiting example uses five input signal streams (A, B, C, D,and E), and eight independent transponders. At time T₀ all five inputstreams exhibit equal power 702, as illustrated in FIG. 7. At time T₁,an operator at the ground uplink terminal may choose to tap 50% of thetotal transponders' power 704 for signal stream A, and 35% of the totaltransponders' power 706 for signal stream B, and 5% of the totaltransponders' power each for steams C, D and E. The operator may thenchange to an input mixing at time T₂ with 60% of the total power 708 forStream A, and 10% of the total power 710 for Streams B, C, D, and E, and100% for Stream A at time slot T₃. As a result, all eight transponderswill respond and provide amplifications with equivalent output EIRPdistributions at T₀, T₁ and T₃ accordingly as illustrated in FIG. 7.

The dynamic allocations of equivalent transponder powers according tothe market demand are done usually by an operator or user through theuplink station transmission or program aggregation facility for a DBSservice. The power allocation variations may be hourly, or in minutes,or in seconds, depending on the market demand and the number oftransponders available. It is the decision of the owners of the DBSservice to make the change and allocate the equivalent powers to thetransponders. The mechanisms by which the transponder powers areallocated are the ratios of the mixtures of the input signal streams. Atan extreme, an operator may turn off some of the input signal streams infavor of allocating more power to the remaining streams and assigningthem with higher EIRPs from all the participating satellites.

III-iv) Embodiment of WFM DBS Satellite System Utilizing MultipleSatellites

In another embodiment of the invention, the WFM DBS power combiningscheme can be implemented to include transponder assets in multiplesatellites at various orbital slots. In this embodiment, the grounduplink stations, or gateway, access multiple satellites via multiplebeam antennas or multiple antennas, each pointed to a correspondingsatellite. Then, the subscriber terminals cost effectively access thedesignated multiple satellites via multiple beam antennas. Analogtechniques can be used to implement effectively a system to combinetransponder powers of say eight individual transponders from two orthree satellites and divide the total power into multiple (<8)transponders. Furthermore, implementation using digital basebandapproach can be very effective in cases when there are more carriers ina single transponder and the total transponder numbers are greater than8 (such as 16 or 32).

III-v) Embodiment of Multiple Satellites Backchannel Calibration UsingWFM

In still another embodiment of the invention, the WFM and WFDM can beused to perform back channel calibrations on mobile satellitecommunications with ground-based beam forming features (GBBF). This typeof satellite usually employs a large antenna reflector (greater than 10meters and less than 30 meters) at L- or S-bands, and has hundreds offully configurable transmit and receive beams, which are essential fordelivering services to small mobile and portable devices. With beamforming performed on the ground uplink segment using WFM and WFDM, thecost and time to deliver a highly flexible satellite are significantlyreduced, since there are less than 100 feeds on board a satelliteassociated with the large reflector and there is no beam formingmechanism on board.

This embodiment of the invention combines the equalized amplitudes,equalized phases, and equalized time-delays in the equalized WFM signalswith associated optimization techniques in order to perform back channelcalibration on mobile satellite communications with ground based beamforming features (GBBF). For receive (Rx) functions the signals capturedby the feeds are transported to the ground facility for furtherprocessing including beam forming. Similarly for transmit (Tx) function,the ground facility will “calculate” the signals for various feeds basedon the multiple beam information.

III-vi) WFM DBS Satellite System Design Example

FIG. 8 illustrates the use of an embodiment of the WFM DBS satellitesystem coupled together with a retired Ku band satellite 800 in orbit,which features 19 transponders 802, each with 36 MHz bandwidth, and with47 dBW EIRP over a coverage area. This example illustrates how theproposed invention, as shown in FIG. 8, is used to combine the powerfrom available transponders in a retired satellite 800 in order todynamically match the market need through the ground facility 804,without modifying the satellite 800 operation, and without modifying thereceiver segment 806. The embodiment of the invention in FIG. 8 is usedto convert the retired Ku band satellite in order to deliver a varietyof services equivalent to that of a satellite with the followingoptional features:

A. 10 transponders

-   -   9 high medium power transponders with 50 dBW EIRP,    -   1 low power transponder with 47 dBW EIRP;    -   all with 36 MHz Bandwidth A RF front-end has an optional        frequency up-converter, a BPF at RF, and an SSPA.        B. 7 transponders    -   4 high medium power transponders with 53 dBW EIRP,    -   1 high medium power transponders with 50 dBW EIRP,    -   1 low power transponder with 47 dBW EIRP;    -   all with 36 MHz Bandwidth        C. Dynamically allocating the resources equivalent of 7        transponders to 19 transponders as demands arise

The reader's attention is directed to all papers and documents which arefiled concurrently with this specification and which are open to publicinspection with this specification, and the contents of all such papersand documents are incorporated herein by reference. All the featuresdisclosed in this specification, (including any accompanying claims,abstract, and drawings) may be replaced by alternative features servingthe same, equivalent or similar purpose, unless expressly statedotherwise. Thus, unless expressly stated otherwise, each featuredisclosed is one example only of a generic series of equivalent orsimilar features.

Furthermore, any element in a claim that does not explicitly state“means for” performing a specified function, or “step for” performing aspecific function, is not to be interpreted as a “means” or “step”clause as specified in 35 U.S.C. Section 112, Paragraph 6.

FIG. 9 900 depicts an operational scenario of coherent power combiningfor signals in return links using two geostationary satellites viawavefront (WF) muxing/demuxing techniques. Spoke-and-hub communicationsnetwork architectures are used for the illustrations. The principles areapplicable to mesh networks and other communications architectures.

There are three segments in the illustration, a ground segment 930, asatellite segment 920, and a user segment 910. The return links arereferred to signal transmissions initiated by the user segment 910,transponded (amplified and frequency translated) by the satellitesegment 920, and received by the ground segment 930. The satellitesegment 920 must feature space assets capable of covering service areasin which users in the user segment 910 residing, and areas wherecommunications hubs in the ground segment 930 are located. The returnlink signals transmitted by a ground user from the user segment 910 arelow-noise amplified, frequency-translated, and then power-amplified bydifferent transponders in various satellites in the satellite segment920 and coherently combined by a hub terminal in the ground segment 930.As a result, the received signals-to-noise-ratio (SNR) of the returnlink signals before a demodulator in the hub terminal of the groundsegment 930 is enhanced accordingly.

For a user terminal in the user segment 910, an input signal stream S(t)is decomposed into M substreams, Sx′(t), where M is integer and M>1. Theinputs of an N-to-N WF muxer 911 consist of M signal ports and N-M probesignal ports, where N>M and N is an integer. The N outputs features thefollowing characteristics

-   -   1. Each of the N outputs is a unique linear combinations of all        N inputs including M signal streams and N-M probing signals        streams;        -   a. The weighting coefficients among various input signals in            each of the N outputs are independent    -   2. Each of the N inputs appears in all N outputs:        -   a. The weighting coefficients on an input over the N-linear            combinations feature unique distribution; the unique            distribution of the weighting coefficients are the            constituting components of a WF vector associated to the            input port.        -   b. Various input ports will associate different WF vectors            among the N-outputs;        -   c. The N WF vectors associated with the N-to-N WF muxer are            mutually orthogonal to one another in an N-dimensional space            in which each of the N-output port representing one of the            N-dimensions.

The N aggregated outputs from the WF muxer 911 are individuallyfrequency up-converted by an array of frequency up-converters 912, andgrouped by frequency-division-multiplex (FDM) muxers 913 for twodifferent satellites 921 and 922 in the satellite segment 920. Group 1and group 2 of muxed signals, Y1(t) and Y2(t) respectively, feature N1and N2 aggregated channels, where N1+N2=N and N1, N2 are positiveintegers. These two groups of muxed signals Y1(t) and Y2(t) areamplified by power amplifiers and then radiated independently by amulti-beam antenna (MBA) 914 aiming for the two designated satellites921 and 922 separately in the satellite segment 920.

For the satellite segment 920, the two satellites 921 and 922independently receive, transpond (or equivalent), and re-radiate the N1and N2 channels of aggregated signals respectively toward a hubterminal. As a result, the two groups of aggregated signals in variouschannels when arriving at the hub terminal will experience differenttime delays, drifts in frequencies and phases, and amplitudeattentions/amplifications. It is important to note that

-   -   1. Each of the M Sx′(t) is replicated N times and appears in all        N1 channels utilized in the first satellite 921, and        concurrently in all N2 channels utilized in the second satellite        922.    -   2. Each of the N-M probing signal streams is replicated N times        and appears in the same N1 utilized channels of the first        satellite 921, and concurrently in the same N2 utilized channels        of the second satellite 922.

For the ground segment 930, a hub terminal features a multi-beam antenna934, input FDM demuxers (I-Muxers) 933, a bank of frequency downconverters 932, an N-to-N WF demuxer 931, and an associated adaptiveequalizer circuitry 931 a. The adaptive equalizers 931 a driven by anoptimization processor 935 utilizing recovered probing signals at theoutputs of N-to-N WF demuxer 931 to iteratively and dynamicallycompensate for the differentials of amplitudes, drifts in frequenciesand phases, and time delays incurred while these wavefronts (WF's) passthough the N1 and N2 propagation channels.

The hub terminal in the ground segment for the return link trafficfeatures low noise amplifiers (LNAs) and band pass filters (BPFs) tocondition (amplify and properly filter) received signals from at leastthe two satellites. The LNAs and BPFs are not depicted. The two FDMdemuxers 933 separate, respectively, the N1 channels of the receivedsignals from the first satellite and N2 channels of the received signalsfrom the second satellite. The frequency converters 932 convert the FDMdemuxed N channel signals to a common frequency, and the adaptiveequalizer 931 a to iteratively equalize N receiving channels by alteringits compensation weighting vector (CWV).

The N-to-N WF demuxer 931 will perform WF demuxing transform on the N(N1+N2) channels of the return link signals to recover M channels ofsignals, and N-M channels of probing signals, which are utilized toequalize the N-propagation channels. At fully equalized conditions, theN WF vectors will become orthogonal again. Since the probing signals areknown a priori, the differences of the recovered probing signals andthose of anticipated versions will be used for propagation paths. “Zero”signals can be used as probing signals, and are ones of possibleversions for probing signals.

An optimization loop to optimize the CWV of the equalizer 931 aiteratively features

-   -   1. a cost function generator (not shown) to map outputs from the        N-M channels of recovered diagnostic/probing signals of the        N-to-N WF demuxer 931 into cost functions as performance indexes        by a cost function generator; whereas the performance indexes        must be positive.    -   2. Cost functions can be generated by measuring the “leakage        signal power among the probing signals.    -   3. Cost functions may also be generated from measurements of        correlations among the N-outputs of the N-to-N WF muxer 931;        especially among the output signals from the signals ports to        those from the probing signal ports    -   4. an optimization processor 935 to sum all the positively        defined cost functions as a total cost; reflecting the current        status of the optimization process; whereas high total cost        indicating poor performance status, low total cost good        performance status, and “zero” total cost representing perfect        optimization status;    -   5. an optimization processor 935 measures the gradients of the        current total cost with respect to the CWV weighting, derives a        new CWV for next update based on a cost minimization algorithm        and then sends the new CWV to the equalizer 931 a for updating        in next iteration.

At steady states, the M recovered outputs of Sx′(t) will be reassembledto constitute a higher data rate received signal stream, S(t) (notshown).

FIG. 10 1000 depicts a scenario of coherent power combining for signalsin return links using two non-geostationary satellites via wavefront(WF) muxing/demuxing techniques. For the current embodiment, aspoke-and-hub communications network architectures for illustrativepurposes. The principles are applicable to mesh networks and otherarchitectures, and would fall under the scope and spirit of the presentinvention. The power combining techniques can be extended to more thantwo satellites which may even be in different orbitals at variousfrequency channels.

Three segments are illustrated; a ground segment 1030, a satellitesegment 1020, and a user segment 1010. The return links are referred tosignal transmissions initiated by the user segment 1010, transponded bythe satellite segment 1020, and received by the ground segment 1030. Thesatellite segment 1020 must feature space assets capable of coveringservice areas in which users in the user segment 1010 reside, and areaswhere communications hubs in the ground segment 1030 are located. Thereturn link signals transmitted by a ground user from the user segment1010 are frequency-translated and then amplified by differenttransponders, or equivalents, in various satellites in the satellitesegment 1020 and coherently combined by a hub terminal As a result, thereceived signals-to-noise-ratios (SNR) of the return link signals beforea demodulator in the hub terminal are enhanced accordingly.

The differences between this figure and FIG. 9 are

-   -   1. Satellite segments; satellites 1021, 1022 and 1023 are not        geostationary assets. There are relative slow motions between        these satellites and fixed ground users    -   2. Antennas 1014 at user segment 1010 are multiple beam tracking        antennas or equivalents, capable of        -   i. tracking the moving individual satellites currently            providing connectivity and relay services to the user            terminals,        -   ii. simultaneously supporting acquisitions of newly arriving            satellites coming up from horizons.    -   3. Antennas 1034 of hub terminals in the ground segment 1030 are        multiple beam tracking antennas or equivalents, capable of        -   i. tracking the moving individual satellites currently            providing connectivity and relay services to the hub            terminals,        -   ii. simultaneously supporting acquisitions of newly arriving            satellites coming up from horizons.

For a user terminal in the user segment 1010, an input signal streamS(t) is decomposed into M substreams, Sx′(t), where M is integer andM>1. The inputs of a N-to-N WF muxer 911 consist of M signal ports andN-M probe signal ports, where N>M. The N outputs features the followingcharacteristics

-   -   1. Each of the N outputs is a unique linear combinations of all        N inputs including M signal streams and N-M probing signals        streams;        -   i. The weighting coefficients among various input signals in            each of the N outputs are independent 2. Each of the N            inputs appears in all N outputs            -   i. The weighting coefficients on an input over the                N-linear combinations features unique distribution; the                unique distribution of the weighting coefficients are                the constituting components of a WF vector.            -   ii. Various inputs will feature different WF vectors                among the N-outputs;            -   iii. The N WF vectors associated with the N-to-N WF                muxer are mutually orthogonal to one another in an                N-dimensional space in which each of the N-output port                is associated with one of the N-dimensions.

The N aggregated outputs from the WF muxer 911 are individuallyfrequency up-converted by an array of frequency up-converters 912, andgrouped by frequency-division-multiplex (FDM) muxers 913 for twodifferent satellites 1021 and 1022 in the satellite segment 1020. Group1 and group 2 of muxed signals, Y1(t) and Y2(t) respectively, feature N1and N2 aggregated channels, where N1+N2=N and N1, N2 are positiveintegers. These two groups of muxed signals Y1(t) and Y2(t) areamplified by power amplifiers and then radiated independently by amultibeams antenna 1014 aiming for the two designated satellites 1021and 1022 separately in the satellite segment 1020.

In the satellite segment 1020, the two slow moving satellites 1021 and1022 independently receive, transpond, and re-radiate toward a hubterminal the N1 and N2 channels of aggregated signals respectively. As aresult, the two groups of aggregated signals in various channels whenarriving at the hub terminal in the ground segment 1030 will experiencedifferent time delays, drifts in frequencies and phases, and amplitudeattentions/amplifications. It is important to notice that

-   -   1. Each of the M Sx′(t) is replicated N times and appears in all        N1 utilized channels of the first satellite 1021, and        concurrently in all N2 utilized channels of the second satellite        1022.    -   2. Each of the N-M probing signal streams is replicated N times        and appears in the same N1 utilized channels of the first        satellite 1021, and concurrently in the same N2 utilized        channels of the second satellite 1022.    -   3. A third satellite 1023 is just coming into an orbital region        where both the user and the hub are visible from the satellite        concurrently.    -   4. Acquisition protocols will enable both the hub and user links        operational for the third satellite 1023.

In the ground segment 1030, a hub terminal features a multi-beamtracking antenna 1034, input FDM demuxers (I-Muxers) 933, a bank offrequency down converters 932, a N-to-N WF demuxer 931, and anassociated adaptive equalizer circuitry 931 a. The adaptive equalizers931 a driven by an optimization processor 935 utilizing recoveredprobing signals at the outputs of the N-to-N WF demuxer 931 toiteratively and dynamically compensate for the differentials ofamplitudes, phases, and time delays incurred while these wavefronts(WF's) passing though the N1 and N2 propagation channels.

The multi-beam tracking antennas or equivalents of the hub terminalsmust handle “soft hand-over” operations engaging and making connectionto an incoming satellite 1023 first before dropping connectivity from anoutgoing satellite 1021.

The hub terminal in the ground segment for the return link trafficfeatures low noise amplifiers (LNAs) and band pass filters (BPFs) tocondition (amplify and properly filter) received signals from at leastthe two satellites. The two FDM demuxers 933 separate the N1 channels ofthe received signals from the first satellite 1021 and N2 channels ofthe received signals from the second satellite 1022. The frequencyconverters 932 convert the FDM demuxed N channel signals to a commonfrequency, and the adaptive equalizer 931 a to iteratively equalize Nreceiving channels by altering its compensation weighting vector (CWV).

The N-to-N WF demuxer will perform WF demuxing transform on the Nchannels of the return link signals to recover M channels of signals,and N-M channels of recovered probing signals, which are utilized toequalize the N-propagation channels. At fully equalized conditions, theN WF vectors will become orthogonal again. Since the probing signals areknown a priori, the differences of the recovered probing signals andthose of anticipated versions will be used for propagation paths. “Zero”signals can be used as probing signals.

An optimization loop to iteratively optimize the CWV of the equalizer931 a features

-   -   1. a cost function generator to map outputs from the N-M        channels of recovered diagnostic signals of the N-to-N WF        demuxer 931 into cost functions as performance indexes by a cost        function generator (not shown); whereas the performance indexes        must be positive,    -   2. Cost functions can be generated by measuring the “leakage        signal power at the probing signals.    -   3. Cost functions may also be generated from measurements of        correlations among the N-outputs of the N-to-N WF muxer 931;        especially among the output signals from the M signals ports to        those from the N-M probing signal ports;    -   4. an optimization processor 935 to sum all the positively        defined cost functions as a total cost; reflecting the current        status of the optimization process; whereas high total cost        indicating poor performance status, low total cost good        performance status, and “zero” total cost representing perfect        optimization status;    -   5. an optimization processor 935 to measure the gradients of the        current total cost with respect to the CWV weighting, derives a        new CWV for next update based on a cost minimization algorithm        and then sends the new CWV to the equalizer 931 a for updating        in next iteration.

At steady states, the M recovered outputs of Sx′(t) will be reassembledto constitute a higher data rate received signal stream, S(t) (notshown).

FIG. 10A depicts a scenario of coherent power combining for signals inforward links using four satellites via wavefront (WF) muxing/demuxingtechniques. We will use spoke-and-hub communications networkarchitectures for illustrations. The principles are applicable to meshnetworks and other architectures, and would fall under the scope andspirit of the present invention. The power combining techniques can beextended to multiple satellites which are in different orbits at variousfrequency bands.

Three segments are illustrated; a ground segment 1030, a satellitesegment 1020, and a user segment 1010. The forward links are referred tosignal transmissions initiated by the ground segment 1030, transpondedor equivalent functions performed by the satellite segment 1020, andreceived by the user segment 1010. The satellite segment 1020 mustfeature space assets capable of covering service areas in which users inthe user segment 1010 residing, and areas where communications hubs inthe ground segment 1030 are located. The forward link signalstransmitted by a ground hub terminal from the ground segment 1030 forvarious user terminals are preprocessed by a 4-to-4 wavefront (WF) muxer911. The diagnostic signals are incorporated at individually inputstreams A, B, C, and D before the WF muxer via additional muxing devices(not shown). These WF mux transformed signals, or WF muxed signals, areradiated to 4 designated satellites via a multibeams antenna 1034. Thesesignals are frequency-translated and then amplified by differenttransponders or equivalents in various satellites in the satellitesegment 1020 upon arriving a satellite. The transponded signals arecaptured by a multibeams antenna 1014 of a user terminal and coherentlycombined via a WF demuxer 931 before demodulators in the user segment1010. Different users will pick up the desired signals by switchingdesignated output ports of the WF demuxers to demodulators accordingly.As a result, the received signals-to-noise-ratios (SNR) of the forwardlink signals in various user terminals are enhanced accordingly.

For a hub terminal in the ground segment 1030, 4 input signal streamA(t), B(t), C(t), and D(t), designated for four different users, arepushed through a 4-to-4 WF muxers before radiated into 4 separatedsatellites, 1021, 1022, 1023, and 1024. As a result, the 4 outputsfeature the following characteristics

-   -   1. Each of the 4 outputs is a unique linear combinations of all        4 inputs including probing signals streams multiplexed in        individual user signals streams;        -   i. The weighting coefficients, (a11, . . . , a44) among            various input signals in each of the 4 outputs are            independent    -   2. Each of the 4 inputs appears in all 4 outputs        -   i. The weighting coefficients on an input over the 4-linear            combinations features unique distribution; the unique            distribution of the weighting coefficients are the            constituting components of a WF vector.        -   ii. Various inputs will feature different WF vectors among            the 4-outputs;            -   1. For the signal A(t), the 4-D WF vector is (a11, a21,                a31, a41);            -   2. For the signal B(t), the 4-D WF vector is (a12, a22,                a32, a42)            -   3. For the signal C(t), the 4-D WF vector is (a13, a23,                a33, a43)            -   4. For the signal D(t), the 4-D WF vector is (a14, a24,                a34, a44)        -   iii. The 4 WF vectors associated with the 4-to-4 WF muxer            are mutually orthogonal to one another in an 4-dimensional            space in which each of the 4-output port is associated with            one of the 4-dimensions.

The 4 aggregated outputs from the WF muxer 911 are individuallyfrequency up-converted by an array of frequency up-converters (notshown), and grouped by frequency-division-multiplex (FDM) muxers (notshown) for the 4 different satellites 1021, 1022, 1023, 1024 in thesatellite segment 1020.

In the satellite segment 1020, the four satellites 1021, 1022, 1023, and1024 independently receive, transpond, and re-radiate toward a userterminal multiple channels of aggregated signals respectively. As aresult, the four groups of aggregated signals in various channels whenarriving at the 4 user terminals in the user segment 1010 willexperience different time delays, drifts in frequencies and phases, andamplitude attentions/amplifications. It is important to notice that

-   -   1. Each of the 4 input signals, (A, B, C, and D), is replicated        4 times and appears in all utilized channels of the first        satellite 1021, and concurrently in all utilized channels of the        second, the third and the fourth satellites 1022, 1023, and        1024.    -   2. The four input signals are completely independent.

In the user segment 1010, each of the four user terminal features amulti-beam tracking antenna 1014, input FDM demuxers (I-Muxers) (notshown), a bank of frequency down converters (not shown), a 4-to-4 WFdemuxer 931, and an associated adaptive equalizer circuitry (not shown).The adaptive equalizers driven by an optimization processor utilizingrecovered probing signals at the outputs of the 4-to-4 WF demuxer 931 toiteratively and dynamically compensate for the differentials ofamplitudes, phases, and time delays incurred while these wavefronts(WF's) passing though the propagation channels.

1-40. (canceled)
 41. A direct broadcasting service (DBS) satellitesystem, comprising: a satellite segment, a ground segment and a usersegment, wherein the ground segment further comprising at least a firstuplink hub terminal, and the user segment further comprisingmulti-beam-antenna (MBA) user terminals; wherein the first uplink hubterminal further comprising: a preprocessor adapted: to perform awavefront multiplexing (WF Muxing) process with at least two inputs ofbroadcasting signals, and at least one input of diagnostic signal andwith at least two concurrent outputs of WF muxed (WFM) broadcastsignals; and a multi-beam-antenna (MBA) antenna for the uplink hubadapted to continuously point to the at least two broadcastingsatellites and to transmit concurrent multiple output channels of the WFmuxed (WFM) broadcast signals to the satellite segment.
 42. The DBSsatellite system of claim 41, wherein the satellite segment furthercomprising at least two broadcasting satellites with common coverageareas for the ground segment and common coverage of DBS satelliteservice areas for the user segment; wherein each satellite furthercomprising many transponders; wherein each transponder is adapted tocarry the WF muxed (WFM) broadcast signals.
 43. The DBS satellite systemof claim 41, wherein the satellite segment further comprising only onebroadcasting satellite with coverage areas for the ground segment andcoverage of DBS satellite service areas for the user segment; whereinthe satellite further comprising many transponders; wherein eachtransponder is adapted to carry the WF muxed (WFM) broadcast signals.44. The DBS satellite system of claim 41, wherein a first MBA userterminal further comprising: a user MBA antenna adapted to receivemultiple channels of the WF muxed (WFM) broadcast signals transponded bythe satellite segment and to continuously track and point to thesatellite segment, and a post-processor adapted to equalize amplitudeand phase propagation differentials among multiple receiving channels onthe transponded WFM broadcast signals; and to perform a wavefrontde-multiplexing (WF demuxing) process on equalized received multipletransponded WFM broadcast signals.
 45. The post-processor of claim 44further comprising recovered diagnostic signals from outputs of the WFdemuxing, wherein the recovered diagnostic signals further adapted tobecome feedback signals for equalizing the propagation differentialsamong the multiple receiving channels for the transponded WFM broadcastsignals.
 46. The satellite segment of the DBS system of claim 42,wherein the at least two satellites of the satellite segment are ingeostationary orbit slots, wherein the at least two satellites furthercomprising common coverage areas for the ground segment and commoncoverage of communication service areas for the user segment.
 47. Thesatellite segment of the DBS system of claim 42, wherein at least one ofthe satellites of the satellite segment is in a non-geostationary orbitslot.
 48. The DBS satellite system of claim 1, wherein the preprocessorof the first uplink hub terminal further comprising a device adapted to:utilize “zero” signals as diagnostic signals by grounding inputdiagnostic channels of the WF muxing processor.
 49. The DBS satellitesystem of claim 41, wherein the preprocessor of the first uplink hubterminal further comprising a plurality of frequency up-convertersadapted to convert the output channels of the WFM signals to a satellitefrequency band, a plurality of frequency-division-multiplex (FDM)multiplexers (muxers) adapted to multiplex the frequency convertedchannels to at least two aggregated signal streams, and a plurality ofpower amplifiers adapted to amplify the at least two FDM muxed signalstreams before radiation by the hub MBA antenna.
 50. The DBS satellitesystem of claim 41, wherein the first MBA user terminal furthercomprising: a plurality of low noise amplifiers (LNAs) and a pluralityof band pass filters adapted to amplify and filter received signals fromthe at least two satellites, a plurality of FDM demuxers adapted toseparate channels of the received signals, a plurality of frequencyconverters adapted to convert the FDM demuxed channel signals to acommon frequency, and an equalizer adapted to iteratively equalizereceiving channels by altering its compensation weight vectors (CWVs)based on outputs of a WF demuxing processor.
 51. The first MBA userterminal of claim 50 further comprising an optimization loop adapted toiteratively optimize the equalizer CWVs, wherein the optimization loopfurther comprising: a cost function generator adapted to map outputs ofrecovered diagnostic signals from said WF demuxer into cost functions asperformance indexes, wherein said performance indexes must be positive,and an optimization processor, further adapted to sum all positivelydefined cost functions as a total cost, wherein high total costindicates poor performance status, low total cost indicates goodperformance status, and zero total cost indicates perfect optimizationstatus, measure gradients of the current total cost with respect to theCWV weighting, derive updated CWVs based on a cost minimizationalgorithm, and send said new CWVs to said equalizer for updating in newiterations.
 52. The first MBA user terminal of claim 50; theoptimization loop adapted to iteratively optimize the equalizer CWVs,further comprising: at least a first cost function generator to generatecost functions by mapping the following into positively definednumerical values: measurements of differences between recovereddiagnostic signals from output channels of the WF demuxer and thecorresponding diagnostic signal inputs known a priori, calculations ofcorrelations between recovered Pf diagnostic signal outputs andrecovered signal outputs, an optimization processor adapted to sum allpositively defined cost functions as a total cost, wherein high totalcost indicates poor performance status, low total cost indicates goodperformance status, and zero total cost indicates perfect optimizationstatus, measure gradients of the current total cost with respect to theCWV weighting, derive updated CWVs based on a cost minimizationalgorithm, and send said new CWVs to said equalizer for updating in newiterations.
 53. The DBS satellite system of claim 41, wherein thesatellite segment further comprising Ka-band satellites in nearequatorial planes and the equatorial plane, wherein the at least twosatellites further comprising common coverage areas for the groundsegment and common coverage of communications service areas for the usersegment.
 54. A method of operating a direct broadcasting service (DBS)satellite system, comprising: a satellite segment, a ground segment anda user segment, wherein the ground segment further comprising at least afirst uplink hub terminal, and the user segment further comprisingmulti-beam-antenna (MBA) user terminals; wherein the method for thefirst hub terminal further comprising the steps of: wavefrontmultiplexing (WF Muxing) with inputs of diagnostic signals andbroadcasting channel signals and with outputs of channels of WF muxed(WFM) broadcast signals, and transmitting the WF muxed (WFM) broadcastsignals to the satellite segment via at least a first MBA hub antenna.55. The method of operating DBS satellite system of claim 54, wherein amethod for satellite segment further comprising steps of operating atleast two broadcasting satellites with common coverage areas for theground segment and common coverage of DBS satellite service areas forthe user segment; wherein methods for each of the broadcastingsatellites further comprising steps of operating many transponders;wherein each transponder is adapted to carry WF muxed (WFM) broadcastsignals with the steps of receiving the WF muxed (WFM) broadcastsignals, translating the received signals to other frequency slots,filtering, amplifying, and then re-radiating the frequency translatedsignals to coverage areas on ground.
 56. The method of operating DBSsatellite system of claim 54, wherein a method for satellite segmentfurther comprising steps of operating only one broadcasting satellitewith coverage areas for the ground segment and coverage of DBS satelliteservice areas for the user segment; wherein methods for the broadcastingsatellite further comprising steps of operating many transponders;wherein each transponder is adapted to carry WF muxed (WFM) broadcastsignals with the steps of receiving the WF muxed (WFM) broadcastsignals, translating the received signals to other frequency slots,filtering, amplifying, and then re-radiating the frequency translatedsignals to coverage areas on ground.
 57. The method of operating DBSsatellite system of claim 54, wherein the method of the first MBA userterminal further comprising: steps of receiving the transponded WF muxed(WFM) broadcast signals from the satellite segment via a user MBAantenna adapted to continuously track and point to the designatedsatellites, and steps of post processing the received WFM broadcastsignals, wherein the steps for the post processing further comprising:equalizing amplitude and phase propagation differentials among receivedchannels, wavefront de-multiplexing (WF demuxing) with inputs of theequalized received transponded WF muxed (WFM) broadcast signals, andwith output channels of recovered broadcast signals and channels ofrecovered diagnostic signals.
 58. The method for the post-processor ofclaim 57 further comprising steps for recovering diagnostic signals fromoutputs of the WF demuxing processor, wherein the recovered diagnosticsignals further adapted to become feedback signals for equalizing thepropagation differentials among the multiple receiving channels for thetransponded WFM broadcast signals.
 59. The method of claim 57, whereinthe method of the first MBA user terminal further comprising: amplifyingand filtering received signals from the at least two satellites,separating the received signal channels, converting the FDM demuxedsignals in multiple channels to a common frequency, and iterativelyequalizing the receive channels by optimizing compensation weightingvectors (CWV).
 60. The method of claim 57, wherein the first MBA userterminal further comprising an optimization loop adapted to iterativelyoptimize the equalizer CWVs, wherein the optimization loop furthercomprising the steps of: mapping diagnostic signal channel outputs intocost functions as performance indexes, summing all positively definedcost functions as a total cost, wherein high total cost indicates poorperformance, low total cost indicates good performance, and “zero” totalcost indicates perfect optimization, measuring current total costgradients with respect to CWV weighting, deriving new CWVs for newupdates, and sending said new CWVs to said equalizer for updating in thenext iterations.